decoding jpg and show imags on TFTLCD whit lpc1768

very question · Jun 5, 2013

Hi dear All
Thank you for your time
I want to decode images with jpg. format and show them on the TFTLCD
in fact I want micro LPC1768 reads images from SD ram and shows them on the TFTLCD.
I searched a lot and also find a link related to my project, but I can't understand what I should do exactly
I found the example for M0 micro in this link but I cant understand the parts of this program and functions
Would you explain it to me and guide me?
http://elm-chan.org/fsw/tjpgd/00index.html

Sumit_ganvir · Jun 5, 2013

hi
Why not you try with MATLAB Image processing Tool . Then sent op via serial port.

very question · Jun 5, 2013

Sumit_ganvir said:
hi
Why not you try with MATLAB Image processing Tool . Then sent op via serial port.

I want to use microcontroller for decoding

very question · Jun 5, 2013

I have this file but I don't know how can't I use them
View attachment src.rar

jayanth.devarayanadurga · Jun 6, 2013

If the code is for LPC then you can use it. There is another project at libstock.com but not for LPC.

very question · Jun 6, 2013

jayanth.devarayanadurga said:
If the code is for LPC then you can use it. There is another project at libstock.com but not for LPC.

thanks
I have code but I don't know how should I use functions to decode images
I paced the code in the last post
please help me to use theam

jayanth.devarayanadurga · Jun 6, 2013

If you post the algorithm to decode JPEG images then I will be able to tell in what order you have to call the functions given in that file.

very question · Jun 6, 2013

in this file has used huffman algoritm

Code:

/*----------------------------------------------------------------------------/
/ TJpgDec - Tiny JPEG Decompressor R0.01a                     (C)ChaN, 2012
/-----------------------------------------------------------------------------/
/ The TJpgDec is a generic JPEG decompressor module for tiny embedded systems.
/ This is a free software that opened for education, research and commercial
/  developments under license policy of following terms.
/
/  Copyright (C) 2012, ChaN, all right reserved.
/
/ * The TJpgDec module is a free software and there is NO WARRANTY.
/ * No restriction on use. You can use, modify and redistribute it for
/   personal, non-profit or commercial products UNDER YOUR RESPONSIBILITY.
/ * Redistributions of source code must retain the above copyright notice.
/
/-----------------------------------------------------------------------------/
/ Oct 04,'11 R0.01  First release.
/ Feb 19,'12 R0.01a Fixed decompression fails when scan starts with an escape seq.
/----------------------------------------------------------------------------*/

#include "tjpgd.h"


/*-----------------------------------------------*/
/* Zigzag-order to raster-order conversion table */
/*-----------------------------------------------*/

#define ZIG(n)	Zig[n]

static
const BYTE Zig[64] = {	/* Zigzag-order to raster-order conversion table */
	 0,  1,  8, 16,  9,  2,  3, 10, 17, 24, 32, 25, 18, 11,  4,  5,
	12, 19, 26, 33, 40, 48, 41, 34, 27, 20, 13,  6,  7, 14, 21, 28,
	35, 42, 49, 56, 57, 50, 43, 36, 29, 22, 15, 23, 30, 37, 44, 51,
	58, 59, 52, 45, 38, 31, 39, 46, 53, 60, 61, 54, 47, 55, 62, 63
};



/*-------------------------------------------------*/
/* Input scale factor of Arai algorithm            */
/* (scaled up 16 bits for fixed point operations)  */
/*-------------------------------------------------*/

#define IPSF(n)	Ipsf[n]

static
const WORD Ipsf[64] = {	/* See also aa_idct.png */
	(WORD)(1.00000*8192), (WORD)(1.38704*8192), (WORD)(1.30656*8192), (WORD)(1.17588*8192), (WORD)(1.00000*8192), (WORD)(0.78570*8192), (WORD)(0.54120*8192), (WORD)(0.27590*8192),
	(WORD)(1.38704*8192), (WORD)(1.92388*8192), (WORD)(1.81226*8192), (WORD)(1.63099*8192), (WORD)(1.38704*8192), (WORD)(1.08979*8192), (WORD)(0.75066*8192), (WORD)(0.38268*8192),
	(WORD)(1.30656*8192), (WORD)(1.81226*8192), (WORD)(1.70711*8192), (WORD)(1.53636*8192), (WORD)(1.30656*8192), (WORD)(1.02656*8192), (WORD)(0.70711*8192), (WORD)(0.36048*8192),
	(WORD)(1.17588*8192), (WORD)(1.63099*8192), (WORD)(1.53636*8192), (WORD)(1.38268*8192), (WORD)(1.17588*8192), (WORD)(0.92388*8192), (WORD)(0.63638*8192), (WORD)(0.32442*8192),
	(WORD)(1.00000*8192), (WORD)(1.38704*8192), (WORD)(1.30656*8192), (WORD)(1.17588*8192), (WORD)(1.00000*8192), (WORD)(0.78570*8192), (WORD)(0.54120*8192), (WORD)(0.27590*8192),
	(WORD)(0.78570*8192), (WORD)(1.08979*8192), (WORD)(1.02656*8192), (WORD)(0.92388*8192), (WORD)(0.78570*8192), (WORD)(0.61732*8192), (WORD)(0.42522*8192), (WORD)(0.21677*8192),
	(WORD)(0.54120*8192), (WORD)(0.75066*8192), (WORD)(0.70711*8192), (WORD)(0.63638*8192), (WORD)(0.54120*8192), (WORD)(0.42522*8192), (WORD)(0.29290*8192), (WORD)(0.14932*8192),
	(WORD)(0.27590*8192), (WORD)(0.38268*8192), (WORD)(0.36048*8192), (WORD)(0.32442*8192), (WORD)(0.27590*8192), (WORD)(0.21678*8192), (WORD)(0.14932*8192), (WORD)(0.07612*8192)
};



/*---------------------------------------------*/
/* Conversion table for fast clipping process  */
/*---------------------------------------------*/

#define BYTECLIP(v) Clip8[(UINT)(v) & 0x3FF]

static
const BYTE Clip8[1024] = {
	/* 0..255 */
	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
	32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
	64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
	96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127,
	128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
	160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191,
	192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223,
	224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255,
	/* 256..511 */
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	/* -512..-257 */
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	/* -256..-1 */
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};




/*-----------------------------------------------------------------------*/
/* Allocate a memory block from memory pool                              */
/*-----------------------------------------------------------------------*/

static
void* alloc_pool (	/* Pointer to allocated memory block (NULL:no memory available) */
	JDEC* jd,		/* Pointer to the decompressor object */
	UINT nd			/* Number of bytes to allocate */
)
{
	char *rp = 0;


	nd = (nd + 3) & ~3;			/* Align block size to the word boundary */

	if (jd->sz_pool >= nd) {
		jd->sz_pool -= nd;
		rp = (char*)jd->pool;			/* Get start of available memory pool */
		jd->pool = (void*)(rp + nd);	/* Allocate requierd bytes */
	}

	return (void*)rp;	/* Return allocated memory block (NULL:no memory to allocate) */
}




/*-----------------------------------------------------------------------*/
/* Create de-quantization and prescaling tables with a DQT segment       */
/*-----------------------------------------------------------------------*/

static
UINT create_qt_tbl (	/* 0:OK, !0:Failed */
	JDEC* jd,			/* Pointer to the decompressor object */
	const BYTE* data,	/* Pointer to the quantizer tables */
	UINT ndata			/* Size of input data */
)
{
	UINT i;
	BYTE d, z;
	LONG *pb;


	while (ndata) {	/* Process all tables in the segment */
		if (ndata < 65) return JDR_FMT1;	/* Err: table size is unaligned */
		ndata -= 65;
		d = *data++;							/* Get table property */
		if (d & 0xF0) return JDR_FMT1;			/* Err: not 8-bit resolution */
		i = d & 3;								/* Get table ID */
		pb = alloc_pool(jd, 64 * sizeof (LONG));/* Allocate a memory block for the table */
		if (!pb) return JDR_MEM1;				/* Err: not enough memory */
		jd->qttbl[i] = pb;						/* Register the table */
		for (i = 0; i < 64; i++) {				/* Load the table */
			z = ZIG(i);							/* Zigzag-order to raster-order conversion */
			pb[z] = (LONG)((DWORD)*data++ * IPSF(z));	/* Apply scale factor of Arai algorithm to the de-quantizers */
		}
	}

	return JDR_OK;
}




/*-----------------------------------------------------------------------*/
/* Create huffman code tables with a DHT segment                         */
/*-----------------------------------------------------------------------*/

static
UINT create_huffman_tbl (	/* 0:OK, !0:Failed */
	JDEC* jd,				/* Pointer to the decompressor object */
	const BYTE* data,		/* Pointer to the packed huffman tables */
	UINT ndata				/* Size of input data */
)
{
	UINT i, j, b, np, cls, num;
	BYTE d, *pb, *pd;
	WORD hc, *ph;


	while (ndata) {	/* Process all tables in the segment */
		if (ndata < 17) return JDR_FMT1;	/* Err: wrong data size */
		ndata -= 17;
		d = *data++;						/* Get table number and class */
		cls = (d >> 4); num = d & 0x0F;		/* class = dc(0)/ac(1), table number = 0/1 */
		if (d & 0xEE) return JDR_FMT1;		/* Err: invalid class/number */
		pb = alloc_pool(jd, 16);			/* Allocate a memory block for the bit distribution table */
		if (!pb) return JDR_MEM1;			/* Err: not enough memory */
		jd->huffbits[num][cls] = pb;
		for (np = i = 0; i < 16; i++) {		/* Load number of patterns for 1 to 16-bit code */
			pb[i] = b = *data++;
			np += b;	/* Get sum of code words for each code */
		}

		ph = alloc_pool(jd, np * sizeof (WORD));/* Allocate a memory block for the code word table */
		if (!ph) return JDR_MEM1;			/* Err: not enough memory */
		jd->huffcode[num][cls] = ph;
		hc = 0;
		for (j = i = 0; i < 16; i++) {		/* Re-build huffman code word table */
			b = pb[i];
			while (b--) ph[j++] = hc++;
			hc <<= 1;
		}

		if (ndata < np) return JDR_FMT1;	/* Err: wrong data size */
		ndata -= np;
		pd = alloc_pool(jd, np);			/* Allocate a memory block for the decoded data */
		if (!pd) return JDR_MEM1;			/* Err: not enough memory */
		jd->huffdata[num][cls] = pd;
		for (i = 0; i < np; i++) {			/* Load decoded data corresponds to each code ward */
			d = *data++;
			if (!cls && d > 11) return JDR_FMT1;
			*pd++ = d;
		}
	}

	return JDR_OK;
}




/*-----------------------------------------------------------------------*/
/* Extract N bits from input stream                                      */
/*-----------------------------------------------------------------------*/

static
INT bitext (	/* >=0: extracted data, <0: error code */
	JDEC* jd,	/* Pointer to the decompressor object */
	UINT nbit	/* Number of bits to extract (1 to 11) */
)
{
	BYTE msk, s, *dp;
	UINT dc, v, f;


	msk = jd->dmsk; dc = jd->dctr; dp = jd->dptr;	/* Bit mask, number of data available, read ptr */
	s = *dp; v = f = 0;
	do {
		if (!msk) {				/* Next byte? */
			if (!dc) {			/* No input data is available, re-fill input buffer */
				dp = jd->inbuf;	/* Top of input buffer */
				dc = jd->infunc(jd, dp, JD_SZBUF);
				if (!dc) return 0 - JDR_INP;	/* Err: read error or wrong stream termination */
			} else {
				dp++;			/* Next data ptr */
			}
			dc--;				/* Decrement number of available bytes */
			if (f) {			/* In flag sequence? */
				f = 0;			/* Exit flag sequence */
				if (*dp != 0) return 0 - JDR_FMT1;	/* Err: unexpected flag is detected (may be collapted data) */
				*dp = s = 0xFF;			/* The flag is a data 0xFF */
			} else {
				s = *dp;				/* Get next data byte */
				if (s == 0xFF) {		/* Is start of flag sequence? */
					f = 1; continue;	/* Enter flag sequence */
				}
			}
			msk = 0x80;		/* Read from MSB */
		}
		v <<= 1;	/* Get a bit */
		if (s & msk) v++;
		msk >>= 1;
		nbit--;
	} while (nbit);
	jd->dmsk = msk; jd->dctr = dc; jd->dptr = dp;

	return (INT)v;
}




/*-----------------------------------------------------------------------*/
/* Extract a huffman decoded data from input stream                      */
/*-----------------------------------------------------------------------*/

static
INT huffext (			/* >=0: decoded data, <0: error code */
	JDEC* jd,			/* Pointer to the decompressor object */
	const BYTE* hbits,	/* Pointer to the bit distribution table */
	const WORD* hcode,	/* Pointer to the code word table */
	const BYTE* hdata	/* Pointer to the data table */
)
{
	BYTE msk, s, *dp;
	UINT dc, v, f, bl, nd;


	msk = jd->dmsk; dc = jd->dctr; dp = jd->dptr;	/* Bit mask, number of data available, read ptr */
	s = *dp; v = f = 0;
	bl = 16;	/* Max code length */
	do {
		if (!msk) {		/* Next byte? */
			if (!dc) {	/* No input data is available, re-fill input buffer */
				dp = jd->inbuf;	/* Top of input buffer */
				dc = jd->infunc(jd, dp, JD_SZBUF);
				if (!dc) return 0 - JDR_INP;	/* Err: read error or wrong stream termination */
			} else {
				dp++;	/* Next data ptr */
			}
			dc--;		/* Decrement number of available bytes */
			if (f) {		/* In flag sequence? */
				f = 0;		/* Exit flag sequence */
				if (*dp != 0)
					return 0 - JDR_FMT1;/* Err: unexpected flag is detected (may be collapted data) */
				*dp = s = 0xFF;			/* The flag is a data 0xFF */
			} else {
				s = *dp;				/* Get next data byte */
				if (s == 0xFF) {		/* Is start of flag sequence? */
					f = 1; continue;	/* Enter flag sequence, get trailing byte */
				}
			}
			msk = 0x80;		/* Read from MSB */
		}
		v <<= 1;	/* Get a bit */
		if (s & msk) v++;
		msk >>= 1;

		for (nd = *hbits++; nd; nd--) {	/* Search the code word in this bit length */
			if (v == *hcode++) {		/* Matched? */
				jd->dmsk = msk; jd->dctr = dc; jd->dptr = dp;
				return *hdata;			/* Return the decoded data */
			}
			hdata++;
		}
		bl--;
	} while (bl);

	return 0 - JDR_FMT1;	/* Err: code not found (may be collapted data) */
}




/*-----------------------------------------------------------------------*/
/* Apply Inverse-DCT in Arai Algorithm (see also aa_idct.png)            */
/*-----------------------------------------------------------------------*/

static
void block_idct (
	LONG* src,	/* Input block data (de-quantized and pre-scaled for Arai Algorithm) */
	BYTE* dst	/* Pointer to the destination to store the block as byte array */
)
{
	const LONG M13 = (LONG)(1.41421*4096), M2 = (LONG)(1.08239*4096), M4 = (LONG)(2.61313*4096), M5 = (LONG)(1.84776*4096);
	LONG v0, v1, v2, v3, v4, v5, v6, v7;
	LONG t10, t11, t12, t13;
	UINT i;

	/* Process columns */
	for (i = 0; i < 8; i++) {
		v0 = src[8 * 0];	/* Get even elements */
		v1 = src[8 * 2];
		v2 = src[8 * 4];
		v3 = src[8 * 6];

		t10 = v0 + v2;		/* Process the even elements */
		t12 = v0 - v2;
		t11 = (v1 - v3) * M13 >> 12;
		v3 += v1;
		t11 -= v3;
		v0 = t10 + v3;
		v3 = t10 - v3;
		v1 = t11 + t12;
		v2 = t12 - t11;

		v4 = src[8 * 7];	/* Get odd elements */
		v5 = src[8 * 1];
		v6 = src[8 * 5];
		v7 = src[8 * 3];

		t10 = v5 - v4;		/* Process the odd elements */
		t11 = v5 + v4;
		t12 = v6 - v7;
		v7 += v6;
		v5 = (t11 - v7) * M13 >> 12;
		v7 += t11;
		t13 = (t10 + t12) * M5 >> 12;
		v4 = t13 - (t10 * M2 >> 12);
		v6 = t13 - (t12 * M4 >> 12) - v7;
		v5 -= v6;
		v4 -= v5;

		src[8 * 0] = v0 + v7;	/* Write-back transformed values */
		src[8 * 7] = v0 - v7;
		src[8 * 1] = v1 + v6;
		src[8 * 6] = v1 - v6;
		src[8 * 2] = v2 + v5;
		src[8 * 5] = v2 - v5;
		src[8 * 3] = v3 + v4;
		src[8 * 4] = v3 - v4;

		src++;	/* Next column */
	}

	/* Process rows */
	src -= 8;
	for (i = 0; i < 8; i++) {
		v0 = src[0] + (128L << 8);	/* Get even elements (remove DC offset (-128) here) */
		v1 = src[2];
		v2 = src[4];
		v3 = src[6];

		t10 = v0 + v2;				/* Process the even elements */
		t12 = v0 - v2;
		t11 = (v1 - v3) * M13 >> 12;
		v3 += v1;
		t11 -= v3;
		v0 = t10 + v3;
		v3 = t10 - v3;
		v1 = t11 + t12;
		v2 = t12 - t11;

		v4 = src[7];				/* Get odd elements */
		v5 = src[1];
		v6 = src[5];
		v7 = src[3];

		t10 = v5 - v4;				/* Process the odd elements */
		t11 = v5 + v4;
		t12 = v6 - v7;
		v7 += v6;
		v5 = (t11 - v7) * M13 >> 12;
		v7 += t11;
		t13 = (t10 + t12) * M5 >> 12;
		v4 = t13 - (t10 * M2 >> 12);
		v6 = t13 - (t12 * M4 >> 12) - v7;
		v5 -= v6;
		v4 -= v5;

		dst[0] = BYTECLIP((v0 + v7) >> 8);	/* Descale the transformed values 8 bits and output */
		dst[7] = BYTECLIP((v0 - v7) >> 8);
		dst[1] = BYTECLIP((v1 + v6) >> 8);
		dst[6] = BYTECLIP((v1 - v6) >> 8);
		dst[2] = BYTECLIP((v2 + v5) >> 8);
		dst[5] = BYTECLIP((v2 - v5) >> 8);
		dst[3] = BYTECLIP((v3 + v4) >> 8);
		dst[4] = BYTECLIP((v3 - v4) >> 8);
		dst += 8;

		src += 8;	/* Next row */
	}
}




/*-----------------------------------------------------------------------*/
/* Load all blocks in the MCU into working buffer                        */
/*-----------------------------------------------------------------------*/

static
JRESULT mcu_load (
	JDEC* jd		/* Pointer to the decompressor object */
)
{
	LONG *tmp = (LONG*)jd->workbuf;	/* Block working buffer for de-quantize and IDCT */
	UINT blk, nby, nbc, i, z, id, cmp;
	INT b, d, e;
	BYTE *bp;
	const BYTE *hb, *hd;
	const WORD *hc;
	const LONG *dqf;


	nby = jd->msx * jd->msy;	/* Number of Y blocks (1, 2 or 4) */
	nbc = 2;					/* Number of C blocks (2) */
	bp = jd->mcubuf;			/* Pointer to the first block */

	for (blk = 0; blk < nby + nbc; blk++) {
		cmp = (blk < nby) ? 0 : blk - nby + 1;	/* Component number 0:Y, 1:Cb, 2:Cr */
		id = cmp ? 1 : 0;						/* Huffman table ID of the component */

		/* Extract a DC element from input stream */
		hb = jd->huffbits[id][0];				/* Huffman table for the DC element */
		hc = jd->huffcode[id][0];
		hd = jd->huffdata[id][0];
		b = huffext(jd, hb, hc, hd);			/* Extract a huffman coded data (bit length) */
		if (b < 0) return 0 - b;				/* Err: invalid code or input */
		d = jd->dcv[cmp];						/* DC value of previous block */
		if (b) {								/* If there is any difference from previous block */
			e = bitext(jd, b);					/* Extract data bits */
			if (e < 0) return 0 - e;			/* Err: input */
			b = 1 << (b - 1);					/* MSB position */
			if (!(e & b)) e -= (b << 1) - 1;	/* Restore sign if needed */
			d += e;								/* Get current value */
			jd->dcv[cmp] = (SHORT)d;			/* Save current DC value for next block */
		}
		dqf = jd->qttbl[jd->qtid[cmp]];			/* De-quantizer table ID for this component */
		tmp[0] = d * dqf[0] >> 8;				/* De-quantize, apply scale factor of Arai algorithm and descale 8 bits */

		/* Extract following 63 AC elements from input stream */
		for (i = 1; i < 64; i++) tmp[i] = 0;	/* Clear rest of elements */
		hb = jd->huffbits[id][1];				/* Huffman table for the AC elements */
		hc = jd->huffcode[id][1];
		hd = jd->huffdata[id][1];
		i = 1;					/* Top of the AC elements */
		do {
			b = huffext(jd, hb, hc, hd);		/* Extract a huffman coded value (zero runs and bit length) */
			if (b == 0) break;					/* EOB? */
			if (b < 0) return 0 - b;			/* Err: invalid code or input error */
			z = (UINT)b >> 4;					/* Number of leading zero elements */
			if (z) {
				i += z;							/* Skip zero elements */
				if (i >= 64) return JDR_FMT1;	/* Too long zero run */
			}
			if (b &= 0x0F) {					/* Bit length */
				d = bitext(jd, b);				/* Extract data bits */
				if (d < 0) return 0 - d;		/* Err: input device */
				b = 1 << (b - 1);				/* MSB position */
				if (!(d & b)) d -= (b << 1) - 1;/* Restore negative value if needed */
				z = ZIG(i);						/* Zigzag-order to raster-order converted index */
				tmp[z] = d * dqf[z] >> 8;		/* De-quantize, apply scale factor of Arai algorithm and descale 8 bits */
			}
		} while (++i < 64);		/* Next AC element */

		if (JD_USE_SCALE && jd->scale == 3)
			*bp = (*tmp / 256) + 128;	/* If scale ratio is 1/8, IDCT can be ommited and only DC element is used */
		else
			block_idct(tmp, bp);		/* Apply IDCT and store the block to the MCU buffer */

		bp += 64;				/* Next block */
	}

	return JDR_OK;	/* All blocks have been loaded successfully */
}




/*-----------------------------------------------------------------------*/
/* Output an MCU: Convert YCrCb to RGB and output it in RGB form         */
/*-----------------------------------------------------------------------*/

static
JRESULT mcu_output (
	JDEC* jd,	/* Pointer to the decompressor object */
	UINT (*outfunc)(JDEC*, void*, JRECT*),	/* RGB output function */
	UINT x,		/* MCU position in the image (left of the MCU) */
	UINT y		/* MCU position in the image (top of the MCU) */
)
{
	const INT CVACC = (sizeof (INT) > 2) ? 1024 : 128;
	UINT ix, iy, mx, my, rx, ry;
	INT yy, cb, cr;
	BYTE *py, *pc, *rgb24;
	JRECT rect;


	mx = jd->msx * 8; my = jd->msy * 8;					/* MCU size (pixel) */
	rx = (x + mx <= jd->width) ? mx : jd->width - x;	/* Output rectangular size (it may be clipped at right/bottom end) */
	ry = (y + my <= jd->height) ? my : jd->height - y;
	if (JD_USE_SCALE) {
		rx >>= jd->scale; ry >>= jd->scale;
		if (!rx || !ry) return JDR_OK;					/* Skip this MCU if all pixel is to be rounded off */
		x >>= jd->scale; y >>= jd->scale;
	}
	rect.left = x; rect.right = x + rx - 1;				/* Rectangular area in the frame buffer */
	rect.top = y; rect.bottom = y + ry - 1;


	if (!JD_USE_SCALE || jd->scale != 3) {	/* Not for 1/8 scaling */

		/* Build an RGB MCU from discrete comopnents */
		rgb24 = (BYTE*)jd->workbuf;
		for (iy = 0; iy < my; iy++) {
			pc = jd->mcubuf;
			py = pc + iy * 8;
			if (my == 16) {		/* Double block height? */
				pc += 64 * 4 + (iy >> 1) * 8;
				if (iy >= 8) py += 64;
			} else {			/* Single block height */
				pc += mx * 8 + iy * 8;
			}
			for (ix = 0; ix < mx; ix++) {
				cb = pc[0] - 128; 	/* Get Cb/Cr component and restore right level */
				cr = pc[64] - 128;
				if (mx == 16) {					/* Double block width? */
					if (ix == 8) py += 64 - 8;	/* Jump to next block if double block heigt */
					pc += ix & 1;				/* Increase chroma pointer every two pixels */
				} else {						/* Single block width */
					pc++;						/* Increase chroma pointer every pixel */
				}
				yy = *py++;			/* Get Y component */

				/* Convert YCbCr to RGB */
				*rgb24++ = /* R */ BYTECLIP(yy + ((INT)(1.402 * CVACC) * cr) / CVACC);
				*rgb24++ = /* G */ BYTECLIP(yy - ((INT)(0.344 * CVACC) * cb + (INT)(0.714 * CVACC) * cr) / CVACC);
				*rgb24++ = /* B */ BYTECLIP(yy + ((INT)(1.772 * CVACC) * cb) / CVACC);
			}
		}

		/* Descale the MCU rectangular if needed */
		if (JD_USE_SCALE && jd->scale) {
			UINT x, y, r, g, b, s, w, a;
			BYTE *op;

			/* Get averaged RGB value of each square correcponds to a pixel */
			s = jd->scale * 2;	/* Bumber of shifts for averaging */
			w = 1 << jd->scale;	/* Width of square */
			a = (mx - w) * 3;	/* Bytes to skip for next line in the square */
			op = (BYTE*)jd->workbuf;
			for (iy = 0; iy < my; iy += w) {
				for (ix = 0; ix < mx; ix += w) {
					rgb24 = (BYTE*)jd->workbuf + (iy * mx + ix) * 3;
					r = g = b = 0;
					for (y = 0; y < w; y++) {	/* Accumulate RGB value in the square */
						for (x = 0; x < w; x++) {
							r += *rgb24++;
							g += *rgb24++;
							b += *rgb24++;
						}
						rgb24 += a;
					}							/* Put the averaged RGB value as a pixel */
					*op++ = (BYTE)(r >> s);
					*op++ = (BYTE)(g >> s);
					*op++ = (BYTE)(b >> s);
				}
			}
		}

	} else {	/* For only 1/8 scaling (left-top pixel in each block are the DC value of the block) */

		/* Build a 1/8 descaled RGB MCU from discrete comopnents */
		rgb24 = (BYTE*)jd->workbuf;
		pc = jd->mcubuf + mx * my;
		cb = pc[0] - 128;		/* Get Cb/Cr component and restore right level */
		cr = pc[64] - 128;
		for (iy = 0; iy < my; iy += 8) {
			py = jd->mcubuf;
			if (iy == 8) py += 64 * 2;
			for (ix = 0; ix < mx; ix += 8) {
				yy = *py;	/* Get Y component */
				py += 64;

				/* Convert YCbCr to RGB */
				*rgb24++ = /* R */ BYTECLIP(yy + ((INT)(1.402 * CVACC) * cr / CVACC));
				*rgb24++ = /* G */ BYTECLIP(yy - ((INT)(0.344 * CVACC) * cb + (INT)(0.714 * CVACC) * cr) / CVACC);
				*rgb24++ = /* B */ BYTECLIP(yy + ((INT)(1.772 * CVACC) * cb / CVACC));
			}
		}
	}

	/* Squeeze up pixel table if a part of MCU is to be truncated */
	mx >>= jd->scale;
	if (rx < mx) {
		BYTE *s, *d;
		UINT x, y;

		s = d = (BYTE*)jd->workbuf;
		for (y = 0; y < ry; y++) {
			for (x = 0; x < rx; x++) {	/* Copy effective pixels */
				*d++ = *s++;
				*d++ = *s++;
				*d++ = *s++;
			}
			s += (mx - rx) * 3;	/* Skip truncated pixels */
		}
	}

	/* Convert RGB888 to RGB565 if needed */
	if (JD_FORMAT == 1) {
		BYTE *s = (BYTE*)jd->workbuf;
		WORD w, *d = (WORD*)s;
		UINT n = rx * ry;

		do {
			w = (*s++ & 0xF8) << 8;		/* RRRRR----------- */
			w |= (*s++ & 0xFC) << 3;	/* -----GGGGGG----- */
			w |= *s++ >> 3;				/* -----------BBBBB */
			*d++ = w;
		} while (--n);
	}

	/* Output the RGB rectangular */
	return outfunc(jd, jd->workbuf, &rect) ? JDR_OK : JDR_INTR; 
}




/*-----------------------------------------------------------------------*/
/* Process restart interval                                              */
/*-----------------------------------------------------------------------*/

static
JRESULT restart (
	JDEC* jd,	/* Pointer to the decompressor object */
	WORD rstn	/* Expected restert sequense number */
)
{
	UINT i, dc;
	WORD d;
	BYTE *dp;


	/* Discard padding bits and get two bytes from the input stream */
	dp = jd->dptr; dc = jd->dctr;
	d = 0;
	for (i = 0; i < 2; i++) {
		if (!dc) {	/* No input data is available, re-fill input buffer */
			dp = jd->inbuf;
			dc = jd->infunc(jd, dp, JD_SZBUF);
			if (!dc) return JDR_INP;
		} else {
			dp++;
		}
		dc--;
		d = (d << 8) | *dp;	/* Get a byte */
	}
	jd->dptr = dp; jd->dctr = dc; jd->dmsk = 0;

	/* Check the marker */
	if ((d & 0xFFD8) != 0xFFD0 || (d & 7) != (rstn & 7))
		return JDR_FMT1;	/* Err: expected RSTn marker is not detected (may be collapted data) */

	/* Reset DC offset */
	jd->dcv[2] = jd->dcv[1] = jd->dcv[0] = 0;

	return JDR_OK;
}




/*-----------------------------------------------------------------------*/
/* Analyze the JPEG image and Initialize decompressor object             */
/*-----------------------------------------------------------------------*/

#define	LDB_WORD(ptr)		(WORD)(((WORD)*((BYTE*)(ptr))<<8)|(WORD)*(BYTE*)((ptr)+1))


JRESULT jd_prepare (
	JDEC* jd,			/* Blank decompressor object */
	UINT (*infunc)(JDEC*, BYTE*, UINT),	/* JPEG strem input function */
	void* pool,			/* Working buffer for the decompression session */
	UINT sz_pool,		/* Size of working buffer */
	void* dev			/* I/O device identifier for the session */
)
{
	BYTE *seg, b;
	WORD marker;
	DWORD ofs;
	UINT n, i, j, len;
	JRESULT rc;


	if (!pool) return JDR_PAR;

	jd->pool = pool;		/* Work memroy */
	jd->sz_pool = sz_pool;	/* Size of given work memory */
	jd->infunc = infunc;	/* Stream input function */
	jd->device = dev;		/* I/O device identifier */
	jd->nrst = 0;			/* No restart interval (default) */

	for (i = 0; i < 2; i++) {	/* Nulls pointers */
		for (j = 0; j < 2; j++) {
			jd->huffbits[i][j] = 0;
			jd->huffcode[i][j] = 0;
			jd->huffdata[i][j] = 0;
		}
	}
	for (i = 0; i < 4; i++) jd->qttbl[i] = 0;

	jd->inbuf = seg = alloc_pool(jd, JD_SZBUF);		/* Allocate stream input buffer */
	if (!seg) return JDR_MEM1;

	if (jd->infunc(jd, seg, 2) != 2) return JDR_INP;/* Check SOI marker */
	if (LDB_WORD(seg) != 0xFFD8) return JDR_FMT1;	/* Err: SOI is not detected */
	ofs = 2;

	for (;;) {
		/* Get a JPEG marker */
		if (jd->infunc(jd, seg, 4) != 4) return JDR_INP;
		marker = LDB_WORD(seg);		/* Marker */
		len = LDB_WORD(seg + 2);	/* Length field */
		if (len <= 2 || (marker >> 8) != 0xFF) return JDR_FMT1;
		len -= 2;		/* Content size excluding length field */
		ofs += 4 + len;	/* Number of bytes loaded */

		switch (marker & 0xFF) {
		case 0xC0:	/* SOF0 (baseline JPEG) */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			jd->width = LDB_WORD(seg+3);		/* Image width in unit of pixel */
			jd->height = LDB_WORD(seg+1);		/* Image height in unit of pixel */
			if (seg[5] != 3) return JDR_FMT3;	/* Err: Supports only Y/Cb/Cr format */

			/* Check three image components */
			for (i = 0; i < 3; i++) {	
				b = seg[7 + 3 * i];							/* Get sampling factor */
				if (!i) {	/* Y component */
					if (b != 0x11 && b != 0x22 && b != 0x21)/* Check sampling factor */
						return JDR_FMT3;					/* Err: Supports only 4:4:4, 4:2:0 or 4:2:2 */
					jd->msx = b >> 4; jd->msy = b & 15;		/* Size of MCU [blocks] */
				} else {	/* Cb/Cr component */
					if (b != 0x11) return JDR_FMT3;			/* Err: Sampling factor of Cr/Cb must be 1 */
				}
				b = seg[8 + 3 * i];							/* Get dequantizer table ID for this component */
				if (b > 3) return JDR_FMT3;					/* Err: Invalid ID */
				jd->qtid[i] = b;
			}
			break;

		case 0xDD:	/* DRI */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			/* Get restart interval (MCUs) */
			jd->nrst = LDB_WORD(seg);
			break;

		case 0xC4:	/* DHT */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			/* Create huffman tables */
			rc = create_huffman_tbl(jd, seg, len);
			if (rc) return rc;
			break;

		case 0xDB:	/* DQT */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			/* Create de-quantizer tables */
			rc = create_qt_tbl(jd, seg, len);
			if (rc) return rc;
			break;

		case 0xDA:	/* SOS */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			if (!jd->width || !jd->height) return JDR_FMT1;	/* Err: Invalid image size */

			if (seg[0] != 3) return JDR_FMT3;				/* Err: Supports only three color components format */

			/* Check if all tables corresponding to each components have been loaded */
			for (i = 0; i < 3; i++) {
				b = seg[2 + 2 * i];	/* Get huffman table ID */
				if (b != 0x00 && b != 0x11)	return JDR_FMT3;	/* Err: Different table number for DC/AC element */
				b = i ? 1 : 0;
				if (!jd->huffbits[b][0] || !jd->huffbits[b][1])	/* Check huffman table for this component */
					return JDR_FMT1;							/* Err: Huffman table not loaded */
				if (!jd->qttbl[jd->qtid[i]]) return JDR_FMT1;	/* Err: Dequantizer table not loaded */
			}

			/* Allocate working buffer for MCU and RGB */
			n = jd->msy * jd->msx;						/* Number of Y blocks in the MCU */
			if (!n) return JDR_FMT1;					/* Err: SOF0 has not been loaded */
			len = n * 64 * 2 + 64;						/* Allocate buffer for IDCT and RGB output */
			if (len < 256) len = 256;					/* but at least 256 byte is required for IDCT */
			jd->workbuf = alloc_pool(jd, len);			/* and it may occupy a part of following MCU working buffer for RGB output */
			if (!jd->workbuf) return JDR_MEM1;			/* Err: not enough memory */
			jd->mcubuf = alloc_pool(jd, (n + 2) * 64);	/* Allocate MCU working buffer */
			if (!jd->mcubuf) return JDR_MEM1;			/* Err: not enough memory */

			/* Pre-load the JPEG data to extract it from the bit stream */
			jd->dptr = seg; jd->dctr = 0; jd->dmsk = 0;	/* Prepare to read bit stream */
			if (ofs %= JD_SZBUF) {						/* Align read offset to JD_SZBUF */
				jd->dctr = jd->infunc(jd, seg + ofs, JD_SZBUF - (UINT)ofs);
				jd->dptr = seg + ofs - 1;
			}

			return JDR_OK;		/* Initialization succeeded. Ready to decompress the JPEG image. */

		case 0xC1:	/* SOF1 */
		case 0xC2:	/* SOF2 */
		case 0xC3:	/* SOF3 */
		case 0xC5:	/* SOF5 */
		case 0xC6:	/* SOF6 */
		case 0xC7:	/* SOF7 */
		case 0xC9:	/* SOF9 */
		case 0xCA:	/* SOF10 */
		case 0xCB:	/* SOF11 */
		case 0xCD:	/* SOF13 */
		case 0xCE:	/* SOF14 */
		case 0xCF:	/* SOF15 */
		case 0xD9:	/* EOI */
			return JDR_FMT3;	/* Unsuppoted JPEG standard (may be progressive JPEG) */

		default:	/* Unknown segment (comment, exif or etc..) */
			/* Skip segment data */
			if (jd->infunc(jd, 0, len) != len)	/* Null pointer specifies to skip bytes of stream */
				return JDR_INP;
		}
	}
}




/*-----------------------------------------------------------------------*/
/* Start to decompress the JPEG picture                                  */
/*-----------------------------------------------------------------------*/

JRESULT jd_decomp (
	JDEC* jd,								/* Initialized decompression object */
	UINT (*outfunc)(JDEC*, void*, JRECT*),	/* RGB output function */
	BYTE scale								/* Output de-scaling factor (0 to 3) */
)
{
	UINT x, y, mx, my;
	WORD rst, rsc;
	JRESULT rc;


	if (scale > (JD_USE_SCALE ? 3 : 0)) return JDR_PAR;
	jd->scale = scale;

	mx = jd->msx * 8; my = jd->msy * 8;			/* Size of the MCU (pixel) */

	jd->dcv[2] = jd->dcv[1] = jd->dcv[0] = 0;	/* Initialize DC values */
	rst = rsc = 0;

	rc = JDR_OK;
	for (y = 0; y < jd->height; y += my) {		/* Vertical loop of MCUs */
		for (x = 0; x < jd->width; x += mx) {	/* Horizontal loop of MCUs */
			if (jd->nrst && rst++ == jd->nrst) {	/* Process restart interval if enabled */
				rc = restart(jd, rsc++);
				if (rc != JDR_OK) return rc;
				rst = 1;
			}
			rc = mcu_load(jd);					/* Load an MCU (decompress huffman coded stream and IDCT) */
			if (rc != JDR_OK) return rc;
			rc = mcu_output(jd, outfunc, x, y);	/* Output the MCU (color space conversion, scaling and output) */
			if (rc != JDR_OK) return rc;
		}
	}

	return rc;
}

jayanth.devarayanadurga · Jun 6, 2013

I didn't ask that. I need the steps involved in displaying a JPEG image. I need to know in which order the functions has to be called to display an image.

very question · Jun 6, 2013

I read this page" http://elm-chan.org/fsw/tjpgd/en/appnote.html "
and I understood The decompression session is divided in two stages. The first stage is to analyze the JPEG image and the second stage is to decompress it.
in that page there is an example that I can't understand it
I opened SD with this code

Code:

fp = fopen ("M:\\JPG\\test.jpg","r");

I don't know how should I use jd_prepare() and jd_decomp()
would you please tell me what should I do?

Code:

/*-----------------------------------------------------------------------*/
/* Analyze the JPEG image and Initialize decompressor object             */
/*-----------------------------------------------------------------------*/

#define	LDB_WORD(ptr)		(WORD)(((WORD)*((BYTE*)(ptr))<<8)|(WORD)*(BYTE*)((ptr)+1))


JRESULT jd_prepare (
	JDEC* jd,			/* Blank decompressor object */
	UINT (*infunc)(JDEC*, BYTE*, UINT),	/* JPEG strem input function */
	void* pool,			/* Working buffer for the decompression session */
	UINT sz_pool,		/* Size of working buffer */
	void* dev			/* I/O device identifier for the session */
)
{
	BYTE *seg, b;
	WORD marker;
	DWORD ofs;
	UINT n, i, j, len;
	JRESULT rc;


	if (!pool) return JDR_PAR;

	jd->pool = pool;		/* Work memroy */
	jd->sz_pool = sz_pool;	/* Size of given work memory */
	jd->infunc = infunc;	/* Stream input function */
	jd->device = dev;		/* I/O device identifier */
	jd->nrst = 0;			/* No restart interval (default) */

	for (i = 0; i < 2; i++) {	/* Nulls pointers */
		for (j = 0; j < 2; j++) {
			jd->huffbits[i][j] = 0;
			jd->huffcode[i][j] = 0;
			jd->huffdata[i][j] = 0;
		}
	}
	for (i = 0; i < 4; i++) jd->qttbl[i] = 0;

	jd->inbuf = seg = alloc_pool(jd, JD_SZBUF);		/* Allocate stream input buffer */
	if (!seg) return JDR_MEM1;

	if (jd->infunc(jd, seg, 2) != 2) return JDR_INP;/* Check SOI marker */
	if (LDB_WORD(seg) != 0xFFD8) return JDR_FMT1;	/* Err: SOI is not detected */
	ofs = 2;

	for (;;) {
		/* Get a JPEG marker */
		if (jd->infunc(jd, seg, 4) != 4) return JDR_INP;
		marker = LDB_WORD(seg);		/* Marker */
		len = LDB_WORD(seg + 2);	/* Length field */
		if (len <= 2 || (marker >> 8) != 0xFF) return JDR_FMT1;
		len -= 2;		/* Content size excluding length field */
		ofs += 4 + len;	/* Number of bytes loaded */

		switch (marker & 0xFF) {
		case 0xC0:	/* SOF0 (baseline JPEG) */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			jd->width = LDB_WORD(seg+3);		/* Image width in unit of pixel */
			jd->height = LDB_WORD(seg+1);		/* Image height in unit of pixel */
			if (seg[5] != 3) return JDR_FMT3;	/* Err: Supports only Y/Cb/Cr format */

			/* Check three image components */
			for (i = 0; i < 3; i++) {	
				b = seg[7 + 3 * i];							/* Get sampling factor */
				if (!i) {	/* Y component */
					if (b != 0x11 && b != 0x22 && b != 0x21)/* Check sampling factor */
						return JDR_FMT3;					/* Err: Supports only 4:4:4, 4:2:0 or 4:2:2 */
					jd->msx = b >> 4; jd->msy = b & 15;		/* Size of MCU [blocks] */
				} else {	/* Cb/Cr component */
					if (b != 0x11) return JDR_FMT3;			/* Err: Sampling factor of Cr/Cb must be 1 */
				}
				b = seg[8 + 3 * i];							/* Get dequantizer table ID for this component */
				if (b > 3) return JDR_FMT3;					/* Err: Invalid ID */
				jd->qtid[i] = b;
			}
			break;

		case 0xDD:	/* DRI */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			/* Get restart interval (MCUs) */
			jd->nrst = LDB_WORD(seg);
			break;

		case 0xC4:	/* DHT */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			/* Create huffman tables */
			rc = create_huffman_tbl(jd, seg, len);
			if (rc) return rc;
			break;

		case 0xDB:	/* DQT */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			/* Create de-quantizer tables */
			rc = create_qt_tbl(jd, seg, len);
			if (rc) return rc;
			break;

		case 0xDA:	/* SOS */
			/* Load segment data */
			if (len > JD_SZBUF) return JDR_MEM2;
			if (jd->infunc(jd, seg, len) != len) return JDR_INP;

			if (!jd->width || !jd->height) return JDR_FMT1;	/* Err: Invalid image size */

			if (seg[0] != 3) return JDR_FMT3;				/* Err: Supports only three color components format */

			/* Check if all tables corresponding to each components have been loaded */
			for (i = 0; i < 3; i++) {
				b = seg[2 + 2 * i];	/* Get huffman table ID */
				if (b != 0x00 && b != 0x11)	return JDR_FMT3;	/* Err: Different table number for DC/AC element */
				b = i ? 1 : 0;
				if (!jd->huffbits[b][0] || !jd->huffbits[b][1])	/* Check huffman table for this component */
					return JDR_FMT1;							/* Err: Huffman table not loaded */
				if (!jd->qttbl[jd->qtid[i]]) return JDR_FMT1;	/* Err: Dequantizer table not loaded */
			}

			/* Allocate working buffer for MCU and RGB */
			n = jd->msy * jd->msx;						/* Number of Y blocks in the MCU */
			if (!n) return JDR_FMT1;					/* Err: SOF0 has not been loaded */
			len = n * 64 * 2 + 64;						/* Allocate buffer for IDCT and RGB output */
			if (len < 256) len = 256;					/* but at least 256 byte is required for IDCT */
			jd->workbuf = alloc_pool(jd, len);			/* and it may occupy a part of following MCU working buffer for RGB output */
			if (!jd->workbuf) return JDR_MEM1;			/* Err: not enough memory */
			jd->mcubuf = alloc_pool(jd, (n + 2) * 64);	/* Allocate MCU working buffer */
			if (!jd->mcubuf) return JDR_MEM1;			/* Err: not enough memory */

			/* Pre-load the JPEG data to extract it from the bit stream */
			jd->dptr = seg; jd->dctr = 0; jd->dmsk = 0;	/* Prepare to read bit stream */
			if (ofs %= JD_SZBUF) {						/* Align read offset to JD_SZBUF */
				jd->dctr = jd->infunc(jd, seg + ofs, JD_SZBUF - (UINT)ofs);
				jd->dptr = seg + ofs - 1;
			}

			return JDR_OK;		/* Initialization succeeded. Ready to decompress the JPEG image. */

		case 0xC1:	/* SOF1 */
		case 0xC2:	/* SOF2 */
		case 0xC3:	/* SOF3 */
		case 0xC5:	/* SOF5 */
		case 0xC6:	/* SOF6 */
		case 0xC7:	/* SOF7 */
		case 0xC9:	/* SOF9 */
		case 0xCA:	/* SOF10 */
		case 0xCB:	/* SOF11 */
		case 0xCD:	/* SOF13 */
		case 0xCE:	/* SOF14 */
		case 0xCF:	/* SOF15 */
		case 0xD9:	/* EOI */
			return JDR_FMT3;	/* Unsuppoted JPEG standard (may be progressive JPEG) */

		default:	/* Unknown segment (comment, exif or etc..) */
			/* Skip segment data */
			if (jd->infunc(jd, 0, len) != len)	/* Null pointer specifies to skip bytes of stream */
				return JDR_INP;
		}
	}
}

Code:

/*-----------------------------------------------------------------------*/
/* Start to decompress the JPEG picture                                  */
/*-----------------------------------------------------------------------*/

JRESULT jd_decomp (
	JDEC* jd,								/* Initialized decompression object */
	UINT (*outfunc)(JDEC*, void*, JRECT*),	/* RGB output function */
	BYTE scale								/* Output de-scaling factor (0 to 3) */
)
{
	UINT x, y, mx, my;
	WORD rst, rsc;
	JRESULT rc;


	if (scale > (JD_USE_SCALE ? 3 : 0)) return JDR_PAR;
	jd->scale = scale;

	mx = jd->msx * 8; my = jd->msy * 8;			/* Size of the MCU (pixel) */

	jd->dcv[2] = jd->dcv[1] = jd->dcv[0] = 0;	/* Initialize DC values */
	rst = rsc = 0;

	rc = JDR_OK;
	for (y = 0; y < jd->height; y += my) {		/* Vertical loop of MCUs */
		for (x = 0; x < jd->width; x += mx) {	/* Horizontal loop of MCUs */
			if (jd->nrst && rst++ == jd->nrst) {	/* Process restart interval if enabled */
				rc = restart(jd, rsc++);
				if (rc != JDR_OK) return rc;
				rst = 1;
			}
			rc = mcu_load(jd);					/* Load an MCU (decompress huffman coded stream and IDCT) */
			if (rc != JDR_OK) return rc;
			rc = mcu_output(jd, outfunc, x, y);	/* Output the MCU (color space conversion, scaling and output) */
			if (rc != JDR_OK) return rc;
		}
	}

	return rc;
}

very question · Jun 6, 2013

nobody help me

pjmelect · Jun 7, 2013

Decoding JPEG images is a difficult task, one that is perhaps not best attempted as a first try. A much easier format to try first would be a BMP or PCX format. Once you can do these then try a JPEG format.

very question · Jun 7, 2013

pjmelect said:
Decoding JPEG images is a difficult task, one that is perhaps not best attempted as a first try. A much easier format to try first would be a BMP or PCX format. Once you can do these then try a JPEG format.

Hello pjmelect
I tried BMP format before but you know It is bigger than JPEG .
My purpose is showing a film on the LCD, so I want to convert that film to JPEG images and show the images one after the other
Is it a good way to show a film on this LCD?
Do you have another idea?
What is the best way to show a film on this LCD with cortex m3 core?
Thanks in advance

pjmelect · Jun 7, 2013

BMP files are large and have a simple format, PCX files are much smaller and have the simplest compression of any file format, JPEG files are smaller and have very complex compression. You should look at PCX and see if the files it produces are small enough.

https://en.wikipedia.org/wiki/PCX

FvM · Jun 9, 2013

Taking a short look at the Tiny JPEG Decompressor project linked in the initial post gives me the impression, that it's basically suited for the intended purpose.

Apparently very question didn't yet understand how the code exactly works respectivly how it has to be used.

But what's the problem? There are example projects for different processors and an application note. All you have to do is to struggle through.

very question · Jun 9, 2013

Re: decoding jpg and show imags on TFTLCD with lpc1768

Thanks Dear FVM
I read application note and see the example but I don't understand it
would you explain which line in the main program load jpeg image and call analyze and decode function and show it in the display

Code:

/*------------------------------------------------------------------------/
/  MARY OLED/SD test program                                              /
/-------------------------------------------------------------------------/
/
/  Copyright (C) 2011, ChaN, all right reserved.
/
/ * This software is a free software and there is NO WARRANTY.
/ * No restriction on use. You can use, modify and redistribute it for
/   personal, non-profit or commercial products UNDER YOUR RESPONSIBILITY.
/ * Redistributions of source code must retain the above copyright notice.
/
/-------------------------------------------------------------------------*/

#include <string.h>
#include "LPC1100.h"
#include "iic.h"
#include "xprintf.h"
#include "uart.h"
#include "diskio.h"
#include "ff.h"
#include "rtc.h"
#include "disp.h"
#include "filer.h"

#define F_CPU	36000000

#define _MODE_STANDALONE	1	/* Commanded by 1:Motion/UART, 0:UART only */


FATFS Fatfs;

char Line[64];	/* Console input buffer */
BYTE Buff[4096] __attribute__ ((aligned(4)));

volatile UINT Timer;	/* 1kHz increment timer */



#if _MODE_STANDALONE
/*--------------------------------------------------------------*/
/* MEMS data aacquisition and motion command processing         */
/*--------------------------------------------------------------*/

static volatile I2CCTRL I2cCtrl;	/* Control structure for I2C transaction */
static volatile int8_t AccBuff[8];	/* I2C read/write buffer */


/*---------------------------------------------*/
/* MEMS data ready interrupt (MEMS INT signal) */

void PIO_1_IRQHandler (void)
{
	GPIO1IC = _BV(9);	/* Clear P1.9 irq */

	if (I2cCtrl.stat) {
		AccBuff[0] = 0x27 | 0x80;	/* Read register 27-2D into AccBuff */
		I2cCtrl.txb = (uint8_t*)AccBuff;
		I2cCtrl.txc = 1;
		I2cCtrl.rxb = (uint8_t*)AccBuff;
		I2cCtrl.rxc = 7;
		i2c0_start(&I2cCtrl);	/* Initiate to read acceleration data from MEMS */
	}
}


/*------------------------------------------------------*/
/* Call-back function called on end of I2C transaction  */

static
void i2c_eot (
	uint8_t stat	/* I2C transaction status */
)
{
	int z;
	static int x, y, cx, cy;
	static uint8_t wc, tm_x, tm_y, tm_z, tm_cnt;


	if (stat != I2C_SUCCEEDED) return;

	z = (int8_t)AccBuff[6];		/* Get Z-axis value */
	if (tm_z < 255) tm_z++;
	if (z >= 50) {				/* Tapped? (>3.5G) */
		tm_x = tm_y = 0;
		if (tm_z >= 40) {		/* Masking time (100ms) */
			tm_z = 0;
			UartCmd = BTN_OK;
		}
	}

	x += (int8_t)AccBuff[2];
	y += (int8_t)AccBuff[4];
	if (++wc == 8) {	/* Accumulate 8 samples and process it (50 processes/sec) */
		if (tm_cnt < 5) {
			cx = x; cy = y;
			tm_cnt++;
		} else {
			x -= cx; y -= cy;
		}

		if (tm_x < 255) tm_x++;
		if (x >= -16 && x <= 16) {
			tm_x = 20;
		} else {
			if ((x <= -50 && tm_x >= 10) || (x <= -32 && tm_x >= 25)) {
				tm_x = 0;
				UartCmd = BTN_RIGHT;
			}
			if ((x >= 50 && tm_x >= 10) || (x >= 32 && tm_x >= 25)) {
				tm_x = 0;
				UartCmd = BTN_LEFT;
			}
		}

		if (tm_y < 255) tm_y++;
		if (y >= -16 && y <= 16) {
			tm_y = 20;
		} else {
			if ((y <= -50 && tm_y >= 10) || (y <= -32 && tm_y >= 25)) {
				tm_y = 0;
				UartCmd = BTN_UP;
			}
			if ((y >= 50 && tm_y >= 10) || (y >= 32 && tm_y >= 25)) {
				tm_y = 0;
				UartCmd = BTN_DOWN;
			}
		}

		wc = x = y = 0;
	}
}


/*-----------------------------------------------*/
/* Start MEMS continuous acc data aacquisition   */

static
void start_mems (void)
{
	int i;

	/* Initialize MEMS sensor (400sps, 8G/fs, XYZ enabled, irq on eoc) */
	AccBuff[0] = 0x20 | 0x80; AccBuff[1] = 0xE7; AccBuff[2] = 0x00; AccBuff[3] = 0x04;
	I2cCtrl.sla = 0x1C;
	I2cCtrl.retry = 0;
	I2cCtrl.eotfunc = i2c_eot;
	I2cCtrl.rxc = 0;
	for (i = 0; i < 2; i++) {
		I2cCtrl.txb = (void*)AccBuff;
		I2cCtrl.txc = 4;
		i2c0_start(&I2cCtrl);
		while (!I2cCtrl.stat) ;
	}

	PIO_1_IRQHandler();	/* Start conversion loop */
	GPIO1IEV = _BV(9);	/* Select interrupt source (rising edge of P1.9 pin) */
	GPIO1IE = _BV(9);	/* Unmask interrupt of P1.9 pin */
	__enable_irqn(PIO_1_IRQn);	/* Enable PIO1 interrupt */
}
#endif


/*---------------------------------------------------------*/
/* User Provided Timer Function for FatFs module           */
/*---------------------------------------------------------*/
/* This is a real time clock service to be called from     */
/* FatFs module. Any valid time must be returned even if   */
/* the system does not support a real time clock.          */
/* This is not required in read-only configuration.        */

DWORD get_fattime (void)
{
	RTC rtc;


	/* Get local time */
	rtc_gettime(&rtc);

	/* Pack date and time into a DWORD variable */
	return	  ((DWORD)(rtc.year - 1980) << 25)
			| ((DWORD)rtc.month << 21)
			| ((DWORD)rtc.mday << 16)
			| ((DWORD)rtc.hour << 11)
			| ((DWORD)rtc.min << 5)
			| ((DWORD)rtc.sec >> 1);
}



/*--------------------------------------------------------------*/
/* 1000Hz interval timer                                         */
/*--------------------------------------------------------------*/

void SysTick_Handler (void)
{
	STCTRL;		/* Clear overflow flag */

	Timer++;		/* Performance counter */
#if DISP_USE_FILE_LOADER
	TmrFrm += 1000;	/* Increment frame time (disp.c) */
#endif
}



/*--------------------------------------------------------------*/
/* Put FatFs result code                                        */
/*--------------------------------------------------------------*/

static
void put_rc (FRESULT rc)
{
	const char *str =
		"OK\0" "DISK_ERR\0" "INT_ERR\0" "NOT_READY\0" "NO_FILE\0" "NO_PATH\0"
		"INVALID_NAME\0" "DENIED\0" "EXIST\0" "INVALID_OBJECT\0" "WRITE_PROTECTED\0"
		"INVALID_DRIVE\0" "NOT_ENABLED\0" "NO_FILE_SYSTEM\0" "MKFS_ABORTED\0" "TIMEOUT\0"
		"LOCKED\0" "NOT_ENOUGH_CORE\0" "TOO_MANY_OPEN_FILES\0";
	FRESULT i;

	for (i = 0; i != rc && *str; i++) {
		while (*str++) ;
	}
	xprintf("rc=%u FR_%s\n", (UINT)rc, str);
}



/*--------------------------------------------------------------*/
/* Initialization and main processing loop                      */
/*--------------------------------------------------------------*/

int main (void)
{
	long p1, p2;
	char *ptr, *ptr2;
	FRESULT res;
	FATFS *fs;
	FIL fil;
	DIR dir;
	FILINFO fno;
	UINT ofs, s1, s2, cnt;
	RTC rtc;


	/* Enable SysTick timer in interval of 1 ms */
	STRELOAD = F_CPU / 1000 - 1;
	STCTRL = 0x07;

	/* Initialize I2C module */
	i2c0_init();

	/* Initialize UART and attach it to xprintf module for console */
	uart0_init();
	xdev_out(uart0_putc);
	xdev_in(uart0_getc);
	xputs("MARY-MB/OB/SR test monitor\n");

	/* Initialize OLED module */
	disp_init();
	xfprintf(disp_putc, "MARY-MB/OB/SR");

#if _MODE_STANDALONE
	start_mems();	/* Start motion detection */
	f_mount(0, &Fatfs);
	filer(Buff, sizeof Buff);
	GPIO1IE = 0;	/* Stop motion detection (mask MEMS interrupt) */
#endif

	for (;;) {
		xputc('>');
		xgets(Line, sizeof Line);
		ptr = Line;
		switch (*ptr++) {

		case 'F' :
			switch (*ptr++) {
			case 'D' :	/* FD - Start filer */
				filer(Buff, sizeof Buff);
				break;
			case 'L' :	/* FL <file> - Launch file loader */
				while (*ptr == ' ') ptr++;
				load_file(ptr, Buff, sizeof Buff);
				break;
			}
			break;

		case 'd' :
			switch (*ptr++) {

			case 'i' :	/* di - Initialize disk */
				xprintf("rc=%d\n", disk_initialize(0));
				break;

			case 'd' :	/* dd <sector> - Dump secrtor */
				if (!xatoi(&ptr, &p2)) break;
				res = disk_read(0, Buff, p2, 1);
				if (res) { xprintf("rc=%d\n", res); break; }
				xprintf("Sector:%lu\n", p2);
				for (ptr2 = (char*)Buff, ofs = 0; ofs < 0x200; ptr2 += 16, ofs += 16)
					put_dump(ptr2, ofs, 16, DW_CHAR);
				break;
			}
			break;

		case 'f' :
			switch (*ptr++) {
			case 'i' :	/* fi - Initialize logical drive */
				put_rc(f_mount(0, &Fatfs));
				break;

			case 'l' :	/* fl [<path>] - Directory listing */
				while (*ptr == ' ') ptr++;
				res = f_opendir(&dir, ptr);
				if (res) { put_rc(res); break; }
				p1 = s1 = s2 = 0;
				for(;;) {
					res = f_readdir(&dir, &fno);
					if ((res != FR_OK) || !fno.fname[0]) break;
					if (fno.fattrib & AM_DIR) {
						s2++;
					} else {
						s1++; p1 += fno.fsize;
					}
					xprintf("%c%c%c%c%c %u/%02u/%02u %02u:%02u %9lu  %s\n", 
							(fno.fattrib & AM_DIR) ? 'D' : '-',
							(fno.fattrib & AM_RDO) ? 'R' : '-',
							(fno.fattrib & AM_HID) ? 'H' : '-',
							(fno.fattrib & AM_SYS) ? 'S' : '-',
							(fno.fattrib & AM_ARC) ? 'A' : '-',
							(fno.fdate >> 9) + 1980, (fno.fdate >> 5) & 15, fno.fdate & 31,
							(fno.ftime >> 11), (fno.ftime >> 5) & 63,
							fno.fsize, &(fno.fname[0]));
				}
				xprintf("%4u File(s),%10lu bytes\n%4u Dir(s)", s1, p1, s2);
				if (f_getfree(ptr, (DWORD*)&p1, &fs) == FR_OK)
					xprintf(", %10luK bytes free\n", p1 * fs->csize / 2);
				break;

			case 'o' :	/* fo <mode> <file> - Open a file */
				if (!xatoi(&ptr, &p1)) break;
				while (*ptr == ' ') ptr++;
				res = f_open(&fil, ptr, (BYTE)p1);
				put_rc(res);
				break;

			case 'c' :	/* fc - Close a file */
				res = f_close(&fil);
				put_rc(res);
				break;

			case 'e' :	/* fe - Seek file pointer */
				if (!xatoi(&ptr, &p1)) break;
				res = f_lseek(&fil, p1);
				put_rc(res);
				if (res == FR_OK)
					xprintf("fptr = %lu(0x%lX)\n", f_tell(&fil), f_tell(&fil));
				break;

			case 'r' :	/* fr <len> - read file */
				if (!xatoi(&ptr, &p1)) break;
				p2 = 0;
				Timer = 0;
				while (p1) {
					if ((UINT)p1 >= sizeof Buff)	{ cnt = sizeof Buff; p1 -= sizeof Buff; }
					else 			{ cnt = (WORD)p1; p1 = 0; }
					res = f_read(&fil, Buff, cnt, &s2);
					if (res != FR_OK) { put_rc(res); break; }
					p2 += s2;
					if (cnt != s2) break;
				}
				s2 = Timer;
				xprintf("%lu bytes read with %lu kB/sec.\n", p2, p2 / s2);
				break;

			case 'd' :	/* fd <len> - read and dump file from current fp */
				if (!xatoi(&ptr, &p1)) break;
				ofs = f_tell(&fil);
				while (p1) {
					if (p1 >= 16)	{ cnt = 16; p1 -= 16; }
					else 			{ cnt = (WORD)p1; p1 = 0; }
					res = f_read(&fil, Buff, cnt, &cnt);
					if (res != FR_OK) { put_rc(res); break; }
					if (!cnt) break;
					put_dump(Buff, ofs, cnt, DW_CHAR);
					ofs += 16;
				}
				break;

			case 'w' :	/* fw <len> <val> - write file */
				if (!xatoi(&ptr, &p1) || !xatoi(&ptr, &p2)) break;
				for (cnt = 0; cnt < sizeof Buff; Buff[cnt++] = 0) ;
				p2 = 0;
				Timer = 0;
				while (p1) {
					if ((UINT)p1 >= sizeof Buff) { cnt = sizeof Buff; p1 -= sizeof Buff; }
					else { cnt = (WORD)p1; p1 = 0; }
					res = f_write(&fil, Buff, cnt, &s2);
					if (res != FR_OK) { put_rc(res); break; }
					p2 += s2;
					if (cnt != s2) break;
				}
				s2 = Timer;
				xprintf("%lu bytes written with %lu kB/sec.\n", p2, p2 / s2);
				break;

			case 'v' :	/* fv - Truncate file */
				put_rc(f_truncate(&fil));
				break;

			case 'n' :	/* fn <old_name> <new_name> - Change file/dir name */
				while (*ptr == ' ') ptr++;
				ptr2 = strchr(ptr, ' ');
				if (!ptr2) break;
				*ptr2++ = 0;
				while (*ptr2 == ' ') ptr2++;
				put_rc(f_rename(ptr, ptr2));
				break;

			case 'u' :	/* fu <name> - Unlink a file or dir */
				while (*ptr == ' ') ptr++;
				put_rc(f_unlink(ptr));
				break;

			case 'k' :	/* fk <name> - Create a directory */
				while (*ptr == ' ') ptr++;
				put_rc(f_mkdir(ptr));
				break;

			case 'g' :	/* fg <path> - Change current directory */
				while (*ptr == ' ') ptr++;
				put_rc(f_chdir(ptr));
				break;

			case 'q' :	/* fq - Show current dir path */
				res = f_getcwd(Line, sizeof Line);
				if (res)
					put_rc(res);
				else
					xprintf("%s\n", Line);
				break;
			}
			break;

		case 't' :	/* t [<year> <mon> <mday> <hour> <min> <sec>] */
			if (xatoi(&ptr, &p1)) {
				rtc.year = (WORD)p1;
				xatoi(&ptr, &p1); rtc.month = (BYTE)p1;
				xatoi(&ptr, &p1); rtc.mday = (BYTE)p1;
				xatoi(&ptr, &p1); rtc.hour = (BYTE)p1;
				xatoi(&ptr, &p1); rtc.min = (BYTE)p1;
				if (!xatoi(&ptr, &p1)) break;
				rtc.sec = (BYTE)p1;
				rtc_settime(&rtc);
			}
			rtc_gettime(&rtc);
			xprintf("%u/%u/%u %02u:%02u:%02u\n", rtc.year, rtc.month, rtc.mday, rtc.hour, rtc.min, rtc.sec);
			break;

		}


	}
}

**broken link removed**

FvM · Jun 9, 2013

The access is through load_file(), which is calling load_jpg() and associated callback functions. You need to look into filer.c and disp.c, too.

very question · Jun 9, 2013

thanks
my compiler is uvision but this example is not for my compiler? which compiler open it?where can I find it?

FvM · Jun 9, 2013

The makefile seems to refer to gcc (Gnu C++), either under Linux or WinARM. It's mostly used with Eclipse IDE.

I don't expect much problems to port the project to Keil Arm compiler.

very question · Jun 9, 2013

would you please explain the process of decoding and showing JPEG step by step
I can open JPEG file from SD but I don't know what should I do in continue
The number of function are a lot so I confused and I don't know the process of use them

decoding jpg and show imags on TFTLCD whit lpc1768

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