| /* |
| * jutils.c |
| * |
| * Copyright (C) 1991-1994, Thomas G. Lane. |
| * 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 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" |
| |
| |
| /* |
| * 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 macros */ |
| #define FMEMCOPY(dest,src,size) MEMCOPY(dest,src,size) |
| #define FMEMZERO(target,size) MEMZERO(target,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)) |
| #define FMEMZERO(target,size) _fmemset((void FAR *)(target), 0, (size_t)(size)) |
| #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, 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 |
| } |
| |
| |
| 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_medium data. */ |
| { |
| #ifdef FMEMZERO |
| FMEMZERO(target, bytestozero); |
| #else |
| register char FAR * ptr = (char FAR *) target; |
| register size_t count; |
| |
| for (count = bytestozero; count > 0; count--) { |
| *ptr++ = 0; |
| } |
| #endif |
| } |