Unit jutils

Classes

Functions

FMEMCOPY -
FMEMZERO - On normal machines we can apply MEMCOPY() and MEMZERO() to sample arrays and coefficient-block arrays.
jcopy_block_row - GLOBAL

GLOBAL
jcopy_sample_rows - GLOBAL

GLOBAL
jdiv_round_up - Arithmetic utilities } {GLOBAL

GLOBAL
jround_up - GLOBAL

GLOBAL
jzero_far - GLOBAL

GLOBAL

Types

Constants

jpeg_natural_order

Variables


Functions


procedure FMEMCOPY(dest,src : pointer; size : size_t);


procedure FMEMZERO(target : pointer; size : size_t);

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

procedure jcopy_block_row (input_row : JBLOCKROW; output_row : JBLOCKROW; num_blocks : JDIMENSION);

GLOBAL

GLOBAL


procedure jcopy_sample_rows (input_array : JSAMPARRAY; source_row : int; output_array : JSAMPARRAY; dest_row : int; num_rows : int; num_cols : JDIMENSION);

GLOBAL

GLOBAL


function jdiv_round_up (a : long; b : long) : long;

Arithmetic utilities } {GLOBAL

GLOBAL


function jround_up (a : long; b : long) : long;

GLOBAL

GLOBAL


procedure jzero_far (target : pointer;{far} bytestozero : size_t);

GLOBAL

GLOBAL


Types


Constants

jpeg_natural_order = (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)

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). } { 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.

Variables