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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228/* * jutils.c * * Copyright (C) 1991-1996, Thomas G. Lane. * Modified 2009-2019 by Guido Vollbeding. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file contains tables and miscellaneous utility routines needed * for both compression and decompression. * Note we prefix all global names with "j" to minimize conflicts with * a surrounding application. */
#define JPEG_INTERNALS#include "jinclude.h"#include "jpeglib.h"
/* * jpeg_zigzag_order[i] is the zigzag-order position of the i'th element * of a DCT block read in natural order (left to right, top to bottom). */
#if 0 /* This table is not actually needed in v6a */
const int jpeg_zigzag_order[DCTSIZE2] = { 0, 1, 5, 6, 14, 15, 27, 28, 2, 4, 7, 13, 16, 26, 29, 42, 3, 8, 12, 17, 25, 30, 41, 43, 9, 11, 18, 24, 31, 40, 44, 53, 10, 19, 23, 32, 39, 45, 52, 54, 20, 22, 33, 38, 46, 51, 55, 60, 21, 34, 37, 47, 50, 56, 59, 61, 35, 36, 48, 49, 57, 58, 62, 63};
#endif
/* * jpeg_natural_order[i] is the natural-order position of the i'th element * of zigzag order. * * When reading corrupted data, the Huffman decoders could attempt * to reference an entry beyond the end of this array (if the decoded * zero run length reaches past the end of the block). To prevent * wild stores without adding an inner-loop test, we put some extra * "63"s after the real entries. This will cause the extra coefficient * to be stored in location 63 of the block, not somewhere random. * The worst case would be a run-length of 15, which means we need 16 * fake entries. */
const int jpeg_natural_order[DCTSIZE2+16] = { 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, 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */ 63, 63, 63, 63, 63, 63, 63, 63};
const int jpeg_natural_order7[7*7+16] = { 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, 14, 21, 28, 35, 42, 49, 50, 43, 36, 29, 22, 30, 37, 44, 51, 52, 45, 38, 46, 53, 54, 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */ 63, 63, 63, 63, 63, 63, 63, 63};
const int jpeg_natural_order6[6*6+16] = { 0, 1, 8, 16, 9, 2, 3, 10, 17, 24, 32, 25, 18, 11, 4, 5, 12, 19, 26, 33, 40, 41, 34, 27, 20, 13, 21, 28, 35, 42, 43, 36, 29, 37, 44, 45, 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */ 63, 63, 63, 63, 63, 63, 63, 63};
const int jpeg_natural_order5[5*5+16] = { 0, 1, 8, 16, 9, 2, 3, 10, 17, 24, 32, 25, 18, 11, 4, 12, 19, 26, 33, 34, 27, 20, 28, 35, 36, 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */ 63, 63, 63, 63, 63, 63, 63, 63};
const int jpeg_natural_order4[4*4+16] = { 0, 1, 8, 16, 9, 2, 3, 10, 17, 24, 25, 18, 11, 19, 26, 27, 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */ 63, 63, 63, 63, 63, 63, 63, 63};
const int jpeg_natural_order3[3*3+16] = { 0, 1, 8, 16, 9, 2, 10, 17, 18, 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */ 63, 63, 63, 63, 63, 63, 63, 63};
const int jpeg_natural_order2[2*2+16] = { 0, 1, 8, 9, 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */ 63, 63, 63, 63, 63, 63, 63, 63};
/* * Arithmetic utilities */
GLOBAL(long)jdiv_round_up (long a, long b)/* Compute a/b rounded up to next integer, ie, ceil(a/b) *//* Assumes a >= 0, b > 0 */{ return (a + b - 1L) / b;}
GLOBAL(long)jround_up (long a, long b)/* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b *//* Assumes a >= 0, b > 0 */{ a += b - 1L; return a - (a % b);}
/* On normal machines we can apply MEMCOPY() and MEMZERO() to sample arrays * and coefficient-block arrays. This won't work on 80x86 because the arrays * are FAR and we're assuming a small-pointer memory model. However, some * DOS compilers provide far-pointer versions of memcpy() and memset() even * in the small-model libraries. These will be used if USE_FMEM is defined. * Otherwise, the routines below do it the hard way. (The performance cost * is not all that great, because these routines aren't very heavily used.) */
#ifndef NEED_FAR_POINTERS /* normal case, same as regular macro */#define FMEMCOPY(dest,src,size) MEMCOPY(dest,src,size)#else /* 80x86 case, define if we can */#ifdef USE_FMEM#define FMEMCOPY(dest,src,size) _fmemcpy((void FAR *)(dest), (const void FAR *)(src), (size_t)(size))#else/* This function is for use by the FMEMZERO macro defined in jpegint.h. * Do not call this function directly, use the FMEMZERO macro instead. */GLOBAL(void)jzero_far (void FAR * target, size_t bytestozero)/* Zero out a chunk of FAR memory. *//* This might be sample-array data, block-array data, or alloc_large data. */{ register char FAR * ptr = (char FAR *) target; register size_t count;
for (count = bytestozero; count > 0; count--) { *ptr++ = 0; }}#endif#endif
GLOBAL(void)jcopy_sample_rows (JSAMPARRAY input_array, int source_row, JSAMPARRAY output_array, int dest_row, int num_rows, JDIMENSION num_cols)/* Copy some rows of samples from one place to another. * num_rows rows are copied from input_array[source_row++] * to output_array[dest_row++]; these areas may overlap for duplication. * The source and destination arrays must be at least as wide as num_cols. */{ register JSAMPROW inptr, outptr;#ifdef FMEMCOPY register size_t count = (size_t) num_cols * SIZEOF(JSAMPLE);#else register JDIMENSION count;#endif register int row;
input_array += source_row; output_array += dest_row;
for (row = num_rows; row > 0; row--) { inptr = *input_array++; outptr = *output_array++;#ifdef FMEMCOPY FMEMCOPY(outptr, inptr, count);#else for (count = num_cols; count > 0; count--) *outptr++ = *inptr++; /* needn't bother with GETJSAMPLE() here */#endif }}
GLOBAL(void)jcopy_block_row (JBLOCKROW input_row, JBLOCKROW output_row, JDIMENSION num_blocks)/* Copy a row of coefficient blocks from one place to another. */{#ifdef FMEMCOPY FMEMCOPY(output_row, input_row, (size_t) num_blocks * (DCTSIZE2 * SIZEOF(JCOEF)));#else register JCOEFPTR inptr, outptr; register long count;
inptr = (JCOEFPTR) input_row; outptr = (JCOEFPTR) output_row; for (count = (long) num_blocks * DCTSIZE2; count > 0; count--) { *outptr++ = *inptr++; }#endif}