/*************************************************************************** * __________ __ ___. * Open \______ \ ____ ____ | | _\_ |__ _______ ___ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ * \/ \/ \/ \/ \/ * * JPEG image viewer * (This is a real mess if it has to be coded in one single C file) * * File scrolling addition (C) 2005 Alexander Spyridakis * Copyright (C) 2004 Jörg Hohensohn aka [IDC]Dragon * Heavily borrowed from the IJG implementation (C) Thomas G. Lane * Small & fast downscaling IDCT (C) 2002 by Guido Vollbeding JPEGclub.org * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * ****************************************************************************/ #include "plugin.h" #include "jpeg_decoder.h" /* for portability of below JPEG code */ #define MEMSET(p,v,c) rb->memset(p,v,c) #define MEMCPY(d,s,c) rb->memcpy(d,s,c) #define INLINE static inline #define ENDIAN_SWAP16(n) n /* only for poor little endian machines */ /**************** begin JPEG code ********************/ INLINE unsigned range_limit(int value) { #if defined(CPU_COLDFIRE) asm ( /* Note: Uses knowledge that only the low byte of the result is used */ "add.l #128,%[v] \n" /* value += 128; */ "cmp.l #255,%[v] \n" /* overflow? */ "bls.b 1f \n" /* no: return value */ "spl.b %[v] \n" /* yes: set low byte to appropriate boundary */ "1: \n" : /* outputs */ [v]"+d"(value) ); return value; #elif defined(CPU_ARM) asm ( /* Note: Uses knowledge that only the low byte of the result is used */ "add %[v], %[v], #128 \n" /* value += 128 */ "cmp %[v], #255 \n" /* out of range 0..255? */ "mvnhi %[v], %[v], asr #31 \n" /* yes: set all bits to ~(sign_bit) */ : /* outputs */ [v]"+r"(value) ); return value; #else value += 128; if(value < 0) return 0; if(value > 255) return 255; return value; #endif } /* IDCT implementation */ #define CONST_BITS 13 #define PASS1_BITS 2 /* Some C compilers fail to reduce "FIX(constant)" at compile time, thus * causing a lot of useless floating-point operations at run time. * To get around this we use the following pre-calculated constants. * If you change CONST_BITS you may want to add appropriate values. * (With a reasonable C compiler, you can just rely on the FIX() macro...) */ #define FIX_0_298631336 2446 /* FIX(0.298631336) */ #define FIX_0_390180644 3196 /* FIX(0.390180644) */ #define FIX_0_541196100 4433 /* FIX(0.541196100) */ #define FIX_0_765366865 6270 /* FIX(0.765366865) */ #define FIX_0_899976223 7373 /* FIX(0.899976223) */ #define FIX_1_175875602 9633 /* FIX(1.175875602) */ #define FIX_1_501321110 12299 /* FIX(1.501321110) */ #define FIX_1_847759065 15137 /* FIX(1.847759065) */ #define FIX_1_961570560 16069 /* FIX(1.961570560) */ #define FIX_2_053119869 16819 /* FIX(2.053119869) */ #define FIX_2_562915447 20995 /* FIX(2.562915447) */ #define FIX_3_072711026 25172 /* FIX(3.072711026) */ /* Multiply an long variable by an long constant to yield an long result. * For 8-bit samples with the recommended scaling, all the variable * and constant values involved are no more than 16 bits wide, so a * 16x16->32 bit multiply can be used instead of a full 32x32 multiply. * For 12-bit samples, a full 32-bit multiplication will be needed. */ #define MULTIPLY16(var,const) (((short) (var)) * ((short) (const))) /* Dequantize a coefficient by multiplying it by the multiplier-table * entry; produce an int result. In this module, both inputs and result * are 16 bits or less, so either int or short multiply will work. */ /* #define DEQUANTIZE(coef,quantval) (((int) (coef)) * (quantval)) */ #define DEQUANTIZE MULTIPLY16 /* Descale and correctly round an int value that's scaled by N bits. * We assume RIGHT_SHIFT rounds towards minus infinity, so adding * the fudge factor is correct for either sign of X. */ #define DESCALE(x,n) (((x) + (1l << ((n)-1))) >> (n)) /* * Perform dequantization and inverse DCT on one block of coefficients, * producing a reduced-size 1x1 output block. */ static void idct1x1(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line) { (void)skip_line; /* unused */ *p_byte = range_limit(inptr[0] * quantptr[0] >> 3); } /* * Perform dequantization and inverse DCT on one block of coefficients, * producing a reduced-size 2x2 output block. */ static void idct2x2(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line) { int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5; unsigned char* outptr; /* Pass 1: process columns from input, store into work array. */ /* Column 0 */ tmp4 = DEQUANTIZE(inptr[8*0], quantptr[8*0]); tmp5 = DEQUANTIZE(inptr[8*1], quantptr[8*1]); tmp0 = tmp4 + tmp5; tmp2 = tmp4 - tmp5; /* Column 1 */ tmp4 = DEQUANTIZE(inptr[8*0+1], quantptr[8*0+1]); tmp5 = DEQUANTIZE(inptr[8*1+1], quantptr[8*1+1]); tmp1 = tmp4 + tmp5; tmp3 = tmp4 - tmp5; /* Pass 2: process 2 rows, store into output array. */ /* Row 0 */ outptr = p_byte; outptr[0] = range_limit((int) DESCALE(tmp0 + tmp1, 3)); outptr[1] = range_limit((int) DESCALE(tmp0 - tmp1, 3)); /* Row 1 */ outptr = p_byte + skip_line; outptr[0] = range_limit((int) DESCALE(tmp2 + tmp3, 3)); outptr[1] = range_limit((int) DESCALE(tmp2 - tmp3, 3)); } /* * Perform dequantization and inverse DCT on one block of coefficients, * producing a reduced-size 4x4 output block. */ static void idct4x4(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line) { int tmp0, tmp2, tmp10, tmp12; int z1, z2, z3; int * wsptr; unsigned char* outptr; int ctr; int workspace[4*4]; /* buffers data between passes */ /* Pass 1: process columns from input, store into work array. */ wsptr = workspace; for (ctr = 0; ctr < 4; ctr++, inptr++, quantptr++, wsptr++) { /* Even part */ tmp0 = DEQUANTIZE(inptr[8*0], quantptr[8*0]); tmp2 = DEQUANTIZE(inptr[8*2], quantptr[8*2]); tmp10 = (tmp0 + tmp2) << PASS1_BITS; tmp12 = (tmp0 - tmp2) << PASS1_BITS; /* Odd part */ /* Same rotation as in the even part of the 8x8 LL&M IDCT */ z2 = DEQUANTIZE(inptr[8*1], quantptr[8*1]); z3 = DEQUANTIZE(inptr[8*3], quantptr[8*3]); z1 = MULTIPLY16(z2 + z3, FIX_0_541196100); tmp0 = DESCALE(z1 + MULTIPLY16(z3, - FIX_1_847759065), CONST_BITS-PASS1_BITS); tmp2 = DESCALE(z1 + MULTIPLY16(z2, FIX_0_765366865), CONST_BITS-PASS1_BITS); /* Final output stage */ wsptr[4*0] = (int) (tmp10 + tmp2); wsptr[4*3] = (int) (tmp10 - tmp2); wsptr[4*1] = (int) (tmp12 + tmp0); wsptr[4*2] = (int) (tmp12 - tmp0); } /* Pass 2: process 4 rows from work array, store into output array. */ wsptr = workspace; for (ctr = 0; ctr < 4; ctr++) { outptr = p_byte + (ctr*skip_line); /* Even part */ tmp0 = (int) wsptr[0]; tmp2 = (int) wsptr[2]; tmp10 = (tmp0 + tmp2) << CONST_BITS; tmp12 = (tmp0 - tmp2) << CONST_BITS; /* Odd part */ /* Same rotation as in the even part of the 8x8 LL&M IDCT */ z2 = (int) wsptr[1]; z3 = (int) wsptr[3]; z1 = MULTIPLY16(z2 + z3, FIX_0_541196100); tmp0 = z1 + MULTIPLY16(z3, - FIX_1_847759065); tmp2 = z1 + MULTIPLY16(z2, FIX_0_765366865); /* Final output stage */ outptr[0] = range_limit((int) DESCALE(tmp10 + tmp2, CONST_BITS+PASS1_BITS+3)); outptr[3] = range_limit((int) DESCALE(tmp10 - tmp2, CONST_BITS+PASS1_BITS+3)); outptr[1] = range_limit((int) DESCALE(tmp12 + tmp0, CONST_BITS+PASS1_BITS+3)); outptr[2] = range_limit((int) DESCALE(tmp12 - tmp0, CONST_BITS+PASS1_BITS+3)); wsptr += 4; /* advance pointer to next row */ } } /* * Perform dequantization and inverse DCT on one block of coefficients. */ static void idct8x8(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line) { long tmp0, tmp1, tmp2, tmp3; long tmp10, tmp11, tmp12, tmp13; long z1, z2, z3, z4, z5; int * wsptr; unsigned char* outptr; int ctr; int workspace[64]; /* buffers data between passes */ /* Pass 1: process columns from input, store into work array. */ /* Note results are scaled up by sqrt(8) compared to a true IDCT; */ /* furthermore, we scale the results by 2**PASS1_BITS. */ wsptr = workspace; for (ctr = 8; ctr > 0; ctr--) { /* Due to quantization, we will usually find that many of the input * coefficients are zero, especially the AC terms. We can exploit this * by short-circuiting the IDCT calculation for any column in which all * the AC terms are zero. In that case each output is equal to the * DC coefficient (with scale factor as needed). * With typical images and quantization tables, half or more of the * column DCT calculations can be simplified this way. */ if ((inptr[8*1] | inptr[8*2] | inptr[8*3] | inptr[8*4] | inptr[8*5] | inptr[8*6] | inptr[8*7]) == 0) { /* AC terms all zero */ int dcval = DEQUANTIZE(inptr[8*0], quantptr[8*0]) << PASS1_BITS; wsptr[8*0] = wsptr[8*1] = wsptr[8*2] = wsptr[8*3] = wsptr[8*4] = wsptr[8*5] = wsptr[8*6] = wsptr[8*7] = dcval; inptr++; /* advance pointers to next column */ quantptr++; wsptr++; continue; } /* Even part: reverse the even part of the forward DCT. */ /* The rotator is sqrt(2)*c(-6). */ z2 = DEQUANTIZE(inptr[8*2], quantptr[8*2]); z3 = DEQUANTIZE(inptr[8*6], quantptr[8*6]); z1 = MULTIPLY16(z2 + z3, FIX_0_541196100); tmp2 = z1 + MULTIPLY16(z3, - FIX_1_847759065); tmp3 = z1 + MULTIPLY16(z2, FIX_0_765366865); z2 = DEQUANTIZE(inptr[8*0], quantptr[8*0]); z3 = DEQUANTIZE(inptr[8*4], quantptr[8*4]); tmp0 = (z2 + z3) << CONST_BITS; tmp1 = (z2 - z3) << CONST_BITS; tmp10 = tmp0 + tmp3; tmp13 = tmp0 - tmp3; tmp11 = tmp1 + tmp2; tmp12 = tmp1 - tmp2; /* Odd part per figure 8; the matrix is unitary and hence its transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively. */ tmp0 = DEQUANTIZE(inptr[8*7], quantptr[8*7]); tmp1 = DEQUANTIZE(inptr[8*5], quantptr[8*5]); tmp2 = DEQUANTIZE(inptr[8*3], quantptr[8*3]); tmp3 = DEQUANTIZE(inptr[8*1], quantptr[8*1]); z1 = tmp0 + tmp3; z2 = tmp1 + tmp2; z3 = tmp0 + tmp2; z4 = tmp1 + tmp3; z5 = MULTIPLY16(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */ tmp0 = MULTIPLY16(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */ tmp1 = MULTIPLY16(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */ tmp2 = MULTIPLY16(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */ tmp3 = MULTIPLY16(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */ z1 = MULTIPLY16(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */ z2 = MULTIPLY16(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */ z3 = MULTIPLY16(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */ z4 = MULTIPLY16(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */ z3 += z5; z4 += z5; tmp0 += z1 + z3; tmp1 += z2 + z4; tmp2 += z2 + z3; tmp3 += z1 + z4; /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */ wsptr[8*0] = (int) DESCALE(tmp10 + tmp3, CONST_BITS-PASS1_BITS); wsptr[8*7] = (int) DESCALE(tmp10 - tmp3, CONST_BITS-PASS1_BITS); wsptr[8*1] = (int) DESCALE(tmp11 + tmp2, CONST_BITS-PASS1_BITS); wsptr[8*6] = (int) DESCALE(tmp11 - tmp2, CONST_BITS-PASS1_BITS); wsptr[8*2] = (int) DESCALE(tmp12 + tmp1, CONST_BITS-PASS1_BITS); wsptr[8*5] = (int) DESCALE(tmp12 - tmp1, CONST_BITS-PASS1_BITS); wsptr[8*3] = (int) DESCALE(tmp13 + tmp0, CONST_BITS-PASS1_BITS); wsptr[8*4] = (int) DESCALE(tmp13 - tmp0, CONST_BITS-PASS1_BITS); inptr++; /* advance pointers to next column */ quantptr++; wsptr++; } /* Pass 2: process rows from work array, store into output array. */ /* Note that we must descale the results by a factor of 8 == 2**3, */ /* and also undo the PASS1_BITS scaling. */ wsptr = workspace; for (ctr = 0; ctr < 8; ctr++) { outptr = p_byte + (ctr*skip_line); /* Rows of zeroes can be exploited in the same way as we did with columns. * However, the column calculation has created many nonzero AC terms, so * the simplification applies less often (typically 5% to 10% of the time). * On machines with very fast multiplication, it's possible that the * test takes more time than it's worth. In that case this section * may be commented out. */ #ifndef NO_ZERO_ROW_TEST if ((wsptr[1] | wsptr[2] | wsptr[3] | wsptr[4] | wsptr[5] | wsptr[6] | wsptr[7]) == 0) { /* AC terms all zero */ unsigned char dcval = range_limit((int) DESCALE((long) wsptr[0], PASS1_BITS+3)); outptr[0] = dcval; outptr[1] = dcval; outptr[2] = dcval; outptr[3] = dcval; outptr[4] = dcval; outptr[5] = dcval; outptr[6] = dcval; outptr[7] = dcval; wsptr += 8; /* advance pointer to next row */ continue; } #endif /* Even part: reverse the even part of the forward DCT. */ /* The rotator is sqrt(2)*c(-6). */ z2 = (long) wsptr[2]; z3 = (long) wsptr[6]; z1 = MULTIPLY16(z2 + z3, FIX_0_541196100); tmp2 = z1 + MULTIPLY16(z3, - FIX_1_847759065); tmp3 = z1 + MULTIPLY16(z2, FIX_0_765366865); tmp0 = ((long) wsptr[0] + (long) wsptr[4]) << CONST_BITS; tmp1 = ((long) wsptr[0] - (long) wsptr[4]) << CONST_BITS; tmp10 = tmp0 + tmp3; tmp13 = tmp0 - tmp3; tmp11 = tmp1 + tmp2; tmp12 = tmp1 - tmp2; /* Odd part per figure 8; the matrix is unitary and hence its * transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively. */ tmp0 = (long) wsptr[7]; tmp1 = (long) wsptr[5]; tmp2 = (long) wsptr[3]; tmp3 = (long) wsptr[1]; z1 = tmp0 + tmp3; z2 = tmp1 + tmp2; z3 = tmp0 + tmp2; z4 = tmp1 + tmp3; z5 = MULTIPLY16(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */ tmp0 = MULTIPLY16(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */ tmp1 = MULTIPLY16(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */ tmp2 = MULTIPLY16(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */ tmp3 = MULTIPLY16(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */ z1 = MULTIPLY16(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */ z2 = MULTIPLY16(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */ z3 = MULTIPLY16(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */ z4 = MULTIPLY16(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */ z3 += z5; z4 += z5; tmp0 += z1 + z3; tmp1 += z2 + z4; tmp2 += z2 + z3; tmp3 += z1 + z4; /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */ outptr[0] = range_limit((int) DESCALE(tmp10 + tmp3, CONST_BITS+PASS1_BITS+3)); outptr[7] = range_limit((int) DESCALE(tmp10 - tmp3, CONST_BITS+PASS1_BITS+3)); outptr[1] = range_limit((int) DESCALE(tmp11 + tmp2, CONST_BITS+PASS1_BITS+3)); outptr[6] = range_limit((int) DESCALE(tmp11 - tmp2, CONST_BITS+PASS1_BITS+3)); outptr[2] = range_limit((int) DESCALE(tmp12 + tmp1, CONST_BITS+PASS1_BITS+3)); outptr[5] = range_limit((int) DESCALE(tmp12 - tmp1, CONST_BITS+PASS1_BITS+3)); outptr[3] = range_limit((int) DESCALE(tmp13 + tmp0, CONST_BITS+PASS1_BITS+3)); outptr[4] = range_limit((int) DESCALE(tmp13 - tmp0, CONST_BITS+PASS1_BITS+3)); wsptr += 8; /* advance pointer to next row */ } } /* JPEG decoder implementation */ /* Preprocess the JPEG JFIF file */ int process_markers(unsigned char* p_src, long size, struct jpeg* p_jpeg) { unsigned char* p_end = p_src + size; int marker_size; /* variable length of marker segment */ int i, j, n; int ret = 0; /* returned flags */ p_jpeg->p_entropy_end = p_end; while (p_src < p_end) { if (*p_src++ != 0xFF) /* no marker? */ { continue; /* discard */ } switch (*p_src++) { case 0xFF: /* Previous FF was fill byte */ p_src--; /* This FF could be start of a marker */ continue; case 0x00: /* Zero stuffed byte - discard */ break; case 0xC0: /* SOF Huff - Baseline DCT */ { ret |= SOF0; marker_size = *p_src++ << 8; /* Highbyte */ marker_size |= *p_src++; /* Lowbyte */ n = *p_src++; /* sample precision (= 8 or 12) */ if (n != 8) { return(-1); /* Unsupported sample precision */ } p_jpeg->y_size = *p_src++ << 8; /* Highbyte */ p_jpeg->y_size |= *p_src++; /* Lowbyte */ p_jpeg->x_size = *p_src++ << 8; /* Highbyte */ p_jpeg->x_size |= *p_src++; /* Lowbyte */ n = (marker_size-2-6)/3; if (*p_src++ != n || (n != 1 && n != 3)) { return(-2); /* Unsupported SOF0 component specification */ } for (i=0; iframeheader[i].ID = *p_src++; /* Component info */ p_jpeg->frameheader[i].horizontal_sampling = *p_src >> 4; p_jpeg->frameheader[i].vertical_sampling = *p_src++ & 0x0F; p_jpeg->frameheader[i].quanttable_select = *p_src++; if (p_jpeg->frameheader[i].horizontal_sampling > 2 || p_jpeg->frameheader[i].vertical_sampling > 2) return -3; /* Unsupported SOF0 subsampling */ } p_jpeg->blocks = n; } break; case 0xC1: /* SOF Huff - Extended sequential DCT*/ case 0xC2: /* SOF Huff - Progressive DCT*/ case 0xC3: /* SOF Huff - Spatial (sequential) lossless*/ case 0xC5: /* SOF Huff - Differential sequential DCT*/ case 0xC6: /* SOF Huff - Differential progressive DCT*/ case 0xC7: /* SOF Huff - Differential spatial*/ case 0xC8: /* SOF Arith - Reserved for JPEG extensions*/ case 0xC9: /* SOF Arith - Extended sequential DCT*/ case 0xCA: /* SOF Arith - Progressive DCT*/ case 0xCB: /* SOF Arith - Spatial (sequential) lossless*/ case 0xCD: /* SOF Arith - Differential sequential DCT*/ case 0xCE: /* SOF Arith - Differential progressive DCT*/ case 0xCF: /* SOF Arith - Differential spatial*/ { return (-4); /* other DCT model than baseline not implemented */ } case 0xC4: /* Define Huffman Table(s) */ { unsigned char* p_temp; ret |= DHT; marker_size = *p_src++ << 8; /* Highbyte */ marker_size |= *p_src++; /* Lowbyte */ p_temp = p_src; while (p_src < p_temp+marker_size-2-17) /* another table */ { int sum = 0; i = *p_src & 0x0F; /* table index */ if (i > 1) { return (-5); /* Huffman table index out of range */ } else if (*p_src++ & 0xF0) /* AC table */ { for (j=0; j<16; j++) { sum += *p_src; p_jpeg->hufftable[i].huffmancodes_ac[j] = *p_src++; } if(16 + sum > AC_LEN) return -10; /* longer than allowed */ for (; j < 16 + sum; j++) p_jpeg->hufftable[i].huffmancodes_ac[j] = *p_src++; } else /* DC table */ { for (j=0; j<16; j++) { sum += *p_src; p_jpeg->hufftable[i].huffmancodes_dc[j] = *p_src++; } if(16 + sum > DC_LEN) return -11; /* longer than allowed */ for (; j < 16 + sum; j++) p_jpeg->hufftable[i].huffmancodes_dc[j] = *p_src++; } } /* while */ p_src = p_temp+marker_size - 2; /* skip possible residue */ } break; case 0xCC: /* Define Arithmetic coding conditioning(s) */ return(-6); /* Arithmetic coding not supported */ case 0xD8: /* Start of Image */ case 0xD9: /* End of Image */ case 0x01: /* for temp private use arith code */ break; /* skip parameterless marker */ case 0xDA: /* Start of Scan */ { ret |= SOS; marker_size = *p_src++ << 8; /* Highbyte */ marker_size |= *p_src++; /* Lowbyte */ n = (marker_size-2-1-3)/2; if (*p_src++ != n || (n != 1 && n != 3)) { return (-7); /* Unsupported SOS component specification */ } for (i=0; iscanheader[i].ID = *p_src++; p_jpeg->scanheader[i].DC_select = *p_src >> 4; p_jpeg->scanheader[i].AC_select = *p_src++ & 0x0F; } p_src += 3; /* skip spectral information */ p_jpeg->p_entropy_data = p_src; p_end = p_src; /* exit while loop */ } break; case 0xDB: /* Define quantization Table(s) */ { ret |= DQT; marker_size = *p_src++ << 8; /* Highbyte */ marker_size |= *p_src++; /* Lowbyte */ n = (marker_size-2)/(QUANT_TABLE_LENGTH+1); /* # of tables */ for (i=0; i= 4) { return (-8); /* Unsupported quantization table */ } /* Read Quantisation table: */ for (j=0; jquanttable[id][j] = *p_src++; } } break; case 0xDD: /* Define Restart Interval */ { marker_size = *p_src++ << 8; /* Highbyte */ marker_size |= *p_src++; /* Lowbyte */ p_jpeg->restart_interval = *p_src++ << 8; /* Highbyte */ p_jpeg->restart_interval |= *p_src++; /* Lowbyte */ p_src += marker_size-4; /* skip segment */ } break; case 0xDC: /* Define Number of Lines */ case 0xDE: /* Define Hierarchical progression */ case 0xDF: /* Expand Reference Component(s) */ case 0xE0: /* Application Field 0*/ case 0xE1: /* Application Field 1*/ case 0xE2: /* Application Field 2*/ case 0xE3: /* Application Field 3*/ case 0xE4: /* Application Field 4*/ case 0xE5: /* Application Field 5*/ case 0xE6: /* Application Field 6*/ case 0xE7: /* Application Field 7*/ case 0xE8: /* Application Field 8*/ case 0xE9: /* Application Field 9*/ case 0xEA: /* Application Field 10*/ case 0xEB: /* Application Field 11*/ case 0xEC: /* Application Field 12*/ case 0xED: /* Application Field 13*/ case 0xEE: /* Application Field 14*/ case 0xEF: /* Application Field 15*/ case 0xFE: /* Comment */ { marker_size = *p_src++ << 8; /* Highbyte */ marker_size |= *p_src++; /* Lowbyte */ p_src += marker_size-2; /* skip segment */ } break; case 0xF0: /* Reserved for JPEG extensions */ case 0xF1: /* Reserved for JPEG extensions */ case 0xF2: /* Reserved for JPEG extensions */ case 0xF3: /* Reserved for JPEG extensions */ case 0xF4: /* Reserved for JPEG extensions */ case 0xF5: /* Reserved for JPEG extensions */ case 0xF6: /* Reserved for JPEG extensions */ case 0xF7: /* Reserved for JPEG extensions */ case 0xF8: /* Reserved for JPEG extensions */ case 0xF9: /* Reserved for JPEG extensions */ case 0xFA: /* Reserved for JPEG extensions */ case 0xFB: /* Reserved for JPEG extensions */ case 0xFC: /* Reserved for JPEG extensions */ case 0xFD: /* Reserved for JPEG extensions */ case 0x02: /* Reserved */ default: return (-9); /* Unknown marker */ } /* switch */ } /* while */ return (ret); /* return flags with seen markers */ } void default_huff_tbl(struct jpeg* p_jpeg) { static const struct huffman_table luma_table = { { 0x00,0x01,0x05,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B }, { 0x00,0x02,0x01,0x03,0x03,0x02,0x04,0x03,0x05,0x05,0x04,0x04,0x00,0x00,0x01,0x7D, 0x01,0x02,0x03,0x00,0x04,0x11,0x05,0x12,0x21,0x31,0x41,0x06,0x13,0x51,0x61,0x07, 0x22,0x71,0x14,0x32,0x81,0x91,0xA1,0x08,0x23,0x42,0xB1,0xC1,0x15,0x52,0xD1,0xF0, 0x24,0x33,0x62,0x72,0x82,0x09,0x0A,0x16,0x17,0x18,0x19,0x1A,0x25,0x26,0x27,0x28, 0x29,0x2A,0x34,0x35,0x36,0x37,0x38,0x39,0x3A,0x43,0x44,0x45,0x46,0x47,0x48,0x49, 0x4A,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0x63,0x64,0x65,0x66,0x67,0x68,0x69, 0x6A,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0x83,0x84,0x85,0x86,0x87,0x88,0x89, 0x8A,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9A,0xA2,0xA3,0xA4,0xA5,0xA6,0xA7, 0xA8,0xA9,0xAA,0xB2,0xB3,0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0xC2,0xC3,0xC4,0xC5, 0xC6,0xC7,0xC8,0xC9,0xCA,0xD2,0xD3,0xD4,0xD5,0xD6,0xD7,0xD8,0xD9,0xDA,0xE1,0xE2, 0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xF1,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8, 0xF9,0xFA } }; static const struct huffman_table chroma_table = { { 0x00,0x03,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,0x00, 0x00,0x00,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B }, { 0x00,0x02,0x01,0x02,0x04,0x04,0x03,0x04,0x07,0x05,0x04,0x04,0x00,0x01,0x02,0x77, 0x00,0x01,0x02,0x03,0x11,0x04,0x05,0x21,0x31,0x06,0x12,0x41,0x51,0x07,0x61,0x71, 0x13,0x22,0x32,0x81,0x08,0x14,0x42,0x91,0xA1,0xB1,0xC1,0x09,0x23,0x33,0x52,0xF0, 0x15,0x62,0x72,0xD1,0x0A,0x16,0x24,0x34,0xE1,0x25,0xF1,0x17,0x18,0x19,0x1A,0x26, 0x27,0x28,0x29,0x2A,0x35,0x36,0x37,0x38,0x39,0x3A,0x43,0x44,0x45,0x46,0x47,0x48, 0x49,0x4A,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0x63,0x64,0x65,0x66,0x67,0x68, 0x69,0x6A,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0x82,0x83,0x84,0x85,0x86,0x87, 0x88,0x89,0x8A,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9A,0xA2,0xA3,0xA4,0xA5, 0xA6,0xA7,0xA8,0xA9,0xAA,0xB2,0xB3,0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0xC2,0xC3, 0xC4,0xC5,0xC6,0xC7,0xC8,0xC9,0xCA,0xD2,0xD3,0xD4,0xD5,0xD6,0xD7,0xD8,0xD9,0xDA, 0xE2,0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8, 0xF9,0xFA } }; MEMCPY(&p_jpeg->hufftable[0], &luma_table, sizeof(luma_table)); MEMCPY(&p_jpeg->hufftable[1], &chroma_table, sizeof(chroma_table)); return; } /* Compute the derived values for a Huffman table */ static void fix_huff_tbl(int* htbl, struct derived_tbl* dtbl) { int p, i, l, si; int lookbits, ctr; char huffsize[257]; unsigned int huffcode[257]; unsigned int code; dtbl->pub = htbl; /* fill in back link */ /* Figure C.1: make table of Huffman code length for each symbol */ /* Note that this is in code-length order. */ p = 0; for (l = 1; l <= 16; l++) { /* all possible code length */ for (i = 1; i <= (int) htbl[l-1]; i++) /* all codes per length */ huffsize[p++] = (char) l; } huffsize[p] = 0; /* Figure C.2: generate the codes themselves */ /* Note that this is in code-length order. */ code = 0; si = huffsize[0]; p = 0; while (huffsize[p]) { while (((int) huffsize[p]) == si) { huffcode[p++] = code; code++; } code <<= 1; si++; } /* Figure F.15: generate decoding tables for bit-sequential decoding */ p = 0; for (l = 1; l <= 16; l++) { if (htbl[l-1]) { dtbl->valptr[l] = p; /* huffval[] index of 1st symbol of code length l */ dtbl->mincode[l] = huffcode[p]; /* minimum code of length l */ p += htbl[l-1]; dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */ } else { dtbl->maxcode[l] = -1; /* -1 if no codes of this length */ } } dtbl->maxcode[17] = 0xFFFFFL; /* ensures huff_DECODE terminates */ /* Compute lookahead tables to speed up decoding. * First we set all the table entries to 0, indicating "too long"; * then we iterate through the Huffman codes that are short enough and * fill in all the entries that correspond to bit sequences starting * with that code. */ MEMSET(dtbl->look_nbits, 0, sizeof(dtbl->look_nbits)); p = 0; for (l = 1; l <= HUFF_LOOKAHEAD; l++) { for (i = 1; i <= (int) htbl[l-1]; i++, p++) { /* l = current code's length, p = its index in huffcode[] & huffval[]. */ /* Generate left-justified code followed by all possible bit sequences */ lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l); for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) { dtbl->look_nbits[lookbits] = l; dtbl->look_sym[lookbits] = htbl[16+p]; lookbits++; } } } } /* zag[i] is the natural-order position of the i'th element of zigzag order. * If the incoming data is corrupted, decode_mcu could attempt to * reference values beyond the end of the array. To avoid a wild store, * we put some extra zeroes after the real entries. */ static const int zag[] = { 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, 0, 0, 0, 0, 0, 0, 0, 0, /* extra entries in case k>63 below */ 0, 0, 0, 0, 0, 0, 0, 0 }; void build_lut(struct jpeg* p_jpeg) { int i; fix_huff_tbl(p_jpeg->hufftable[0].huffmancodes_dc, &p_jpeg->dc_derived_tbls[0]); fix_huff_tbl(p_jpeg->hufftable[0].huffmancodes_ac, &p_jpeg->ac_derived_tbls[0]); fix_huff_tbl(p_jpeg->hufftable[1].huffmancodes_dc, &p_jpeg->dc_derived_tbls[1]); fix_huff_tbl(p_jpeg->hufftable[1].huffmancodes_ac, &p_jpeg->ac_derived_tbls[1]); /* build the dequantization tables for the IDCT (De-ZiZagged) */ for (i=0; i<64; i++) { p_jpeg->qt_idct[0][zag[i]] = p_jpeg->quanttable[0][i]; p_jpeg->qt_idct[1][zag[i]] = p_jpeg->quanttable[1][i]; } for (i=0; i<4; i++) p_jpeg->store_pos[i] = i; /* default ordering */ /* assignments for the decoding of blocks */ if (p_jpeg->frameheader[0].horizontal_sampling == 2 && p_jpeg->frameheader[0].vertical_sampling == 1) { /* 4:2:2 */ p_jpeg->blocks = 4; p_jpeg->x_mbl = (p_jpeg->x_size+15) / 16; p_jpeg->x_phys = p_jpeg->x_mbl * 16; p_jpeg->y_mbl = (p_jpeg->y_size+7) / 8; p_jpeg->y_phys = p_jpeg->y_mbl * 8; p_jpeg->mcu_membership[0] = 0; /* Y1=Y2=0, U=1, V=2 */ p_jpeg->mcu_membership[1] = 0; p_jpeg->mcu_membership[2] = 1; p_jpeg->mcu_membership[3] = 2; p_jpeg->tab_membership[0] = 0; /* DC, DC, AC, AC */ p_jpeg->tab_membership[1] = 0; p_jpeg->tab_membership[2] = 1; p_jpeg->tab_membership[3] = 1; p_jpeg->subsample_x[0] = 1; p_jpeg->subsample_x[1] = 2; p_jpeg->subsample_x[2] = 2; p_jpeg->subsample_y[0] = 1; p_jpeg->subsample_y[1] = 1; p_jpeg->subsample_y[2] = 1; } if (p_jpeg->frameheader[0].horizontal_sampling == 1 && p_jpeg->frameheader[0].vertical_sampling == 2) { /* 4:2:2 vertically subsampled */ p_jpeg->store_pos[1] = 2; /* block positions are mirrored */ p_jpeg->store_pos[2] = 1; p_jpeg->blocks = 4; p_jpeg->x_mbl = (p_jpeg->x_size+7) / 8; p_jpeg->x_phys = p_jpeg->x_mbl * 8; p_jpeg->y_mbl = (p_jpeg->y_size+15) / 16; p_jpeg->y_phys = p_jpeg->y_mbl * 16; p_jpeg->mcu_membership[0] = 0; /* Y1=Y2=0, U=1, V=2 */ p_jpeg->mcu_membership[1] = 0; p_jpeg->mcu_membership[2] = 1; p_jpeg->mcu_membership[3] = 2; p_jpeg->tab_membership[0] = 0; /* DC, DC, AC, AC */ p_jpeg->tab_membership[1] = 0; p_jpeg->tab_membership[2] = 1; p_jpeg->tab_membership[3] = 1; p_jpeg->subsample_x[0] = 1; p_jpeg->subsample_x[1] = 1; p_jpeg->subsample_x[2] = 1; p_jpeg->subsample_y[0] = 1; p_jpeg->subsample_y[1] = 2; p_jpeg->subsample_y[2] = 2; } else if (p_jpeg->frameheader[0].horizontal_sampling == 2 && p_jpeg->frameheader[0].vertical_sampling == 2) { /* 4:2:0 */ p_jpeg->blocks = 6; p_jpeg->x_mbl = (p_jpeg->x_size+15) / 16; p_jpeg->x_phys = p_jpeg->x_mbl * 16; p_jpeg->y_mbl = (p_jpeg->y_size+15) / 16; p_jpeg->y_phys = p_jpeg->y_mbl * 16; p_jpeg->mcu_membership[0] = 0; p_jpeg->mcu_membership[1] = 0; p_jpeg->mcu_membership[2] = 0; p_jpeg->mcu_membership[3] = 0; p_jpeg->mcu_membership[4] = 1; p_jpeg->mcu_membership[5] = 2; p_jpeg->tab_membership[0] = 0; p_jpeg->tab_membership[1] = 0; p_jpeg->tab_membership[2] = 0; p_jpeg->tab_membership[3] = 0; p_jpeg->tab_membership[4] = 1; p_jpeg->tab_membership[5] = 1; p_jpeg->subsample_x[0] = 1; p_jpeg->subsample_x[1] = 2; p_jpeg->subsample_x[2] = 2; p_jpeg->subsample_y[0] = 1; p_jpeg->subsample_y[1] = 2; p_jpeg->subsample_y[2] = 2; } else if (p_jpeg->frameheader[0].horizontal_sampling == 1 && p_jpeg->frameheader[0].vertical_sampling == 1) { /* 4:4:4 */ /* don't overwrite p_jpeg->blocks */ p_jpeg->x_mbl = (p_jpeg->x_size+7) / 8; p_jpeg->x_phys = p_jpeg->x_mbl * 8; p_jpeg->y_mbl = (p_jpeg->y_size+7) / 8; p_jpeg->y_phys = p_jpeg->y_mbl * 8; p_jpeg->mcu_membership[0] = 0; p_jpeg->mcu_membership[1] = 1; p_jpeg->mcu_membership[2] = 2; p_jpeg->tab_membership[0] = 0; p_jpeg->tab_membership[1] = 1; p_jpeg->tab_membership[2] = 1; p_jpeg->subsample_x[0] = 1; p_jpeg->subsample_x[1] = 1; p_jpeg->subsample_x[2] = 1; p_jpeg->subsample_y[0] = 1; p_jpeg->subsample_y[1] = 1; p_jpeg->subsample_y[2] = 1; } else { /* error */ } } /* * These functions/macros provide the in-line portion of bit fetching. * Use check_bit_buffer to ensure there are N bits in get_buffer * before using get_bits, peek_bits, or drop_bits. * check_bit_buffer(state,n,action); * Ensure there are N bits in get_buffer; if suspend, take action. * val = get_bits(n); * Fetch next N bits. * val = peek_bits(n); * Fetch next N bits without removing them from the buffer. * drop_bits(n); * Discard next N bits. * The value N should be a simple variable, not an expression, because it * is evaluated multiple times. */ INLINE void check_bit_buffer(struct bitstream* pb, int nbits) { if (pb->bits_left < nbits) { /* nbits is <= 16, so I can always refill 2 bytes in this case */ unsigned char byte; byte = *pb->next_input_byte++; if (byte == 0xFF) /* legal marker can be byte stuffing or RSTm */ { /* simplification: just skip the (one-byte) marker code */ pb->next_input_byte++; } pb->get_buffer = (pb->get_buffer << 8) | byte; byte = *pb->next_input_byte++; if (byte == 0xFF) /* legal marker can be byte stuffing or RSTm */ { /* simplification: just skip the (one-byte) marker code */ pb->next_input_byte++; } pb->get_buffer = (pb->get_buffer << 8) | byte; pb->bits_left += 16; } } INLINE int get_bits(struct bitstream* pb, int nbits) { return ((int) (pb->get_buffer >> (pb->bits_left -= nbits))) & (BIT_N(nbits)-1); } INLINE int peek_bits(struct bitstream* pb, int nbits) { return ((int) (pb->get_buffer >> (pb->bits_left - nbits))) & (BIT_N(nbits)-1); } INLINE void drop_bits(struct bitstream* pb, int nbits) { pb->bits_left -= nbits; } /* re-synchronize to entropy data (skip restart marker) */ static void search_restart(struct bitstream* pb) { pb->next_input_byte--; /* we may have overread it, taking 2 bytes */ /* search for a non-byte-padding marker, has to be RSTm or EOS */ while (pb->next_input_byte < pb->input_end && (pb->next_input_byte[-2] != 0xFF || pb->next_input_byte[-1] == 0x00)) { pb->next_input_byte++; } pb->bits_left = 0; } /* Figure F.12: extend sign bit. */ #define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x)) static const int extend_test[16] = /* entry n is 2**(n-1) */ { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }; #if (__GNUC__ >= 6) #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wshift-negative-value" #endif static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */ { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1, ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1, ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1, ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 }; #if (__GNUC__ >= 6) #pragma GCC diagnostic pop #endif /* Decode a single value */ INLINE int huff_decode_dc(struct bitstream* bs, struct derived_tbl* tbl) { int nb, look, s, r; check_bit_buffer(bs, HUFF_LOOKAHEAD); look = peek_bits(bs, HUFF_LOOKAHEAD); if ((nb = tbl->look_nbits[look]) != 0) { drop_bits(bs, nb); s = tbl->look_sym[look]; check_bit_buffer(bs, s); r = get_bits(bs, s); s = HUFF_EXTEND(r, s); } else { /* slow_DECODE(s, HUFF_LOOKAHEAD+1)) < 0); */ long code; nb=HUFF_LOOKAHEAD+1; check_bit_buffer(bs, nb); code = get_bits(bs, nb); while (code > tbl->maxcode[nb]) { code <<= 1; check_bit_buffer(bs, 1); code |= get_bits(bs, 1); nb++; } if (nb > 16) /* error in Huffman */ { s=0; /* fake a zero, this is most safe */ } else { s = tbl->pub[16 + tbl->valptr[nb] + ((int) (code - tbl->mincode[nb])) ]; check_bit_buffer(bs, s); r = get_bits(bs, s); s = HUFF_EXTEND(r, s); } } /* end slow decode */ return s; } INLINE int huff_decode_ac(struct bitstream* bs, struct derived_tbl* tbl) { int nb, look, s; check_bit_buffer(bs, HUFF_LOOKAHEAD); look = peek_bits(bs, HUFF_LOOKAHEAD); if ((nb = tbl->look_nbits[look]) != 0) { drop_bits(bs, nb); s = tbl->look_sym[look]; } else { /* slow_DECODE(s, HUFF_LOOKAHEAD+1)) < 0); */ long code; nb=HUFF_LOOKAHEAD+1; check_bit_buffer(bs, nb); code = get_bits(bs, nb); while (code > tbl->maxcode[nb]) { code <<= 1; check_bit_buffer(bs, 1); code |= get_bits(bs, 1); nb++; } if (nb > 16) /* error in Huffman */ { s=0; /* fake a zero, this is most safe */ } else { s = tbl->pub[16 + tbl->valptr[nb] + ((int) (code - tbl->mincode[nb])) ]; } } /* end slow decode */ return s; } #ifdef HAVE_LCD_COLOR /* JPEG decoder variant for YUV decoding, into 3 different planes */ /* Note: it keeps the original color subsampling, even if resized. */ int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[3], int downscale, void (*pf_progress)(int current, int total)) { struct bitstream bs; /* bitstream "object" */ int block[64]; /* decoded DCT coefficients */ int width, height; int skip_line[3]; /* bytes from one line to the next (skip_line) */ int skip_strip[3], skip_mcu[3]; /* bytes to next DCT row / column */ int i, x, y; /* loop counter */ unsigned char* p_line[3] = {p_pixel[0], p_pixel[1], p_pixel[2]}; unsigned char* p_byte[3]; /* bitmap pointer */ void (*pf_idct)(unsigned char*, int*, int*, int); /* selected IDCT */ int k_need; /* AC coefficients needed up to here */ int zero_need; /* init the block with this many zeros */ int last_dc_val[3] = {0, 0, 0}; /* or 128 for chroma? */ int store_offs[4]; /* memory offsets: order of Y11 Y12 Y21 Y22 U V */ int restart = p_jpeg->restart_interval; /* MCUs until restart marker */ /* pick the IDCT we want, determine how to work with coefs */ if (downscale == 1) { pf_idct = idct8x8; k_need = 64; /* all */ zero_need = 63; /* all */ } else if (downscale == 2) { pf_idct = idct4x4; k_need = 25; /* this far in zig-zag to cover 4*4 */ zero_need = 27; /* clear this far in linear order */ } else if (downscale == 4) { pf_idct = idct2x2; k_need = 5; /* this far in zig-zag to cover 2*2 */ zero_need = 9; /* clear this far in linear order */ } else if (downscale == 8) { pf_idct = idct1x1; k_need = 0; /* no AC, not needed */ zero_need = 0; /* no AC, not needed */ } else return -1; /* not supported */ /* init bitstream, fake a restart to make it start */ bs.get_buffer = 0; bs.next_input_byte = p_jpeg->p_entropy_data; bs.bits_left = 0; bs.input_end = p_jpeg->p_entropy_end; width = p_jpeg->x_phys / downscale; height = p_jpeg->y_phys / downscale; for (i=0; i<3; i++) /* calculate some strides */ { skip_line[i] = width / p_jpeg->subsample_x[i]; skip_strip[i] = skip_line[i] * (height / p_jpeg->y_mbl) / p_jpeg->subsample_y[i]; skip_mcu[i] = width/p_jpeg->x_mbl / p_jpeg->subsample_x[i]; } /* prepare offsets about where to store the different blocks */ store_offs[p_jpeg->store_pos[0]] = 0; store_offs[p_jpeg->store_pos[1]] = 8 / downscale; /* to the right */ store_offs[p_jpeg->store_pos[2]] = width * 8 / downscale; /* below */ store_offs[p_jpeg->store_pos[3]] = store_offs[1] + store_offs[2]; /* r+b */ for(y=0; yy_mbl && bs.next_input_byte <= bs.input_end; y++) { for (i=0; i<3; i++) /* scan line init */ { p_byte[i] = p_line[i]; p_line[i] += skip_strip[i]; } for (x=0; xx_mbl; x++) { int blkn; /* Outer loop handles each block in the MCU */ for (blkn = 0; blkn < p_jpeg->blocks; blkn++) { /* Decode a single block's worth of coefficients */ int k = 1; /* coefficient index */ int s, r; /* huffman values */ int ci = p_jpeg->mcu_membership[blkn]; /* component index */ int ti = p_jpeg->tab_membership[blkn]; /* table index */ struct derived_tbl* dctbl = &p_jpeg->dc_derived_tbls[ti]; struct derived_tbl* actbl = &p_jpeg->ac_derived_tbls[ti]; /* Section F.2.2.1: decode the DC coefficient difference */ s = huff_decode_dc(&bs, dctbl); last_dc_val[ci] += s; block[0] = last_dc_val[ci]; /* output it (assumes zag[0] = 0) */ /* coefficient buffer must be cleared */ MEMSET(block+1, 0, zero_need*sizeof(block[0])); /* Section F.2.2.2: decode the AC coefficients */ for (; k < k_need; k++) { s = huff_decode_ac(&bs, actbl); r = s >> 4; s &= 15; if (s) { k += r; check_bit_buffer(&bs, s); r = get_bits(&bs, s); block[zag[k]] = HUFF_EXTEND(r, s); } else { if (r != 15) { k = 64; break; } k += r; } } /* for k */ /* In this path we just discard the values */ for (; k < 64; k++) { s = huff_decode_ac(&bs, actbl); r = s >> 4; s &= 15; if (s) { k += r; check_bit_buffer(&bs, s); drop_bits(&bs, s); } else { if (r != 15) break; k += r; } } /* for k */ if (ci == 0) { /* Y component needs to bother about block store */ pf_idct(p_byte[0]+store_offs[blkn], block, p_jpeg->qt_idct[ti], skip_line[0]); } else { /* chroma */ pf_idct(p_byte[ci], block, p_jpeg->qt_idct[ti], skip_line[ci]); } } /* for blkn */ p_byte[0] += skip_mcu[0]; /* unrolled for (i=0; i<3; i++) loop */ p_byte[1] += skip_mcu[1]; p_byte[2] += skip_mcu[2]; if (p_jpeg->restart_interval && --restart == 0) { /* if a restart marker is due: */ restart = p_jpeg->restart_interval; /* count again */ search_restart(&bs); /* align the bitstream */ last_dc_val[0] = last_dc_val[1] = last_dc_val[2] = 0; /* reset decoder */ } } /* for x */ if (pf_progress != NULL) pf_progress(y, p_jpeg->y_mbl-1); /* notify about decoding progress */ } /* for y */ return 0; /* success */ } #else /* !HAVE_LCD_COLOR */ /* a JPEG decoder specialized in decoding only the luminance (b&w) */ int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[1], int downscale, void (*pf_progress)(int current, int total)) { struct bitstream bs; /* bitstream "object" */ int block[64]; /* decoded DCT coefficients */ int width, height; int skip_line; /* bytes from one line to the next (skip_line) */ int skip_strip, skip_mcu; /* bytes to next DCT row / column */ int x, y; /* loop counter */ unsigned char* p_line = p_pixel[0]; unsigned char* p_byte; /* bitmap pointer */ void (*pf_idct)(unsigned char*, int*, int*, int); /* selected IDCT */ int k_need; /* AC coefficients needed up to here */ int zero_need; /* init the block with this many zeros */ int last_dc_val = 0; int store_offs[4]; /* memory offsets: order of Y11 Y12 Y21 Y22 U V */ int restart = p_jpeg->restart_interval; /* MCUs until restart marker */ /* pick the IDCT we want, determine how to work with coefs */ if (downscale == 1) { pf_idct = idct8x8; k_need = 64; /* all */ zero_need = 63; /* all */ } else if (downscale == 2) { pf_idct = idct4x4; k_need = 25; /* this far in zig-zag to cover 4*4 */ zero_need = 27; /* clear this far in linear order */ } else if (downscale == 4) { pf_idct = idct2x2; k_need = 5; /* this far in zig-zag to cover 2*2 */ zero_need = 9; /* clear this far in linear order */ } else if (downscale == 8) { pf_idct = idct1x1; k_need = 0; /* no AC, not needed */ zero_need = 0; /* no AC, not needed */ } else return -1; /* not supported */ /* init bitstream, fake a restart to make it start */ bs.get_buffer = 0; bs.next_input_byte = p_jpeg->p_entropy_data; bs.bits_left = 0; bs.input_end = p_jpeg->p_entropy_end; width = p_jpeg->x_phys / downscale; height = p_jpeg->y_phys / downscale; skip_line = width; skip_strip = skip_line * (height / p_jpeg->y_mbl); skip_mcu = (width/p_jpeg->x_mbl); /* prepare offsets about where to store the different blocks */ store_offs[p_jpeg->store_pos[0]] = 0; store_offs[p_jpeg->store_pos[1]] = 8 / downscale; /* to the right */ store_offs[p_jpeg->store_pos[2]] = width * 8 / downscale; /* below */ store_offs[p_jpeg->store_pos[3]] = store_offs[1] + store_offs[2]; /* r+b */ for(y=0; yy_mbl && bs.next_input_byte <= bs.input_end; y++) { p_byte = p_line; p_line += skip_strip; for (x=0; xx_mbl; x++) { int blkn; /* Outer loop handles each block in the MCU */ for (blkn = 0; blkn < p_jpeg->blocks; blkn++) { /* Decode a single block's worth of coefficients */ int k = 1; /* coefficient index */ int s, r; /* huffman values */ int ci = p_jpeg->mcu_membership[blkn]; /* component index */ int ti = p_jpeg->tab_membership[blkn]; /* table index */ struct derived_tbl* dctbl = &p_jpeg->dc_derived_tbls[ti]; struct derived_tbl* actbl = &p_jpeg->ac_derived_tbls[ti]; /* Section F.2.2.1: decode the DC coefficient difference */ s = huff_decode_dc(&bs, dctbl); if (ci == 0) /* only for Y component */ { last_dc_val += s; block[0] = last_dc_val; /* output it (assumes zag[0] = 0) */ /* coefficient buffer must be cleared */ MEMSET(block+1, 0, zero_need*sizeof(block[0])); /* Section F.2.2.2: decode the AC coefficients */ for (; k < k_need; k++) { s = huff_decode_ac(&bs, actbl); r = s >> 4; s &= 15; if (s) { k += r; check_bit_buffer(&bs, s); r = get_bits(&bs, s); block[zag[k]] = HUFF_EXTEND(r, s); } else { if (r != 15) { k = 64; break; } k += r; } } /* for k */ } /* In this path we just discard the values */ for (; k < 64; k++) { s = huff_decode_ac(&bs, actbl); r = s >> 4; s &= 15; if (s) { k += r; check_bit_buffer(&bs, s); drop_bits(&bs, s); } else { if (r != 15) break; k += r; } } /* for k */ if (ci == 0) { /* only for Y component */ pf_idct(p_byte+store_offs[blkn], block, p_jpeg->qt_idct[ti], skip_line); } } /* for blkn */ p_byte += skip_mcu; if (p_jpeg->restart_interval && --restart == 0) { /* if a restart marker is due: */ restart = p_jpeg->restart_interval; /* count again */ search_restart(&bs); /* align the bitstream */ last_dc_val = 0; /* reset decoder */ } } /* for x */ if (pf_progress != NULL) pf_progress(y, p_jpeg->y_mbl-1); /* notify about decoding progress */ } /* for y */ return 0; /* success */ } #endif /* !HAVE_LCD_COLOR */ /**************** end JPEG code ********************/