darkkirb/old-exhal
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index 4 bytes instead of 3

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(since 4 is the smallest back reference anyway; this doesn't have nearly
the same effect on speed as 2-3 did though)
This commit is contained in:
devinacker 2013-12-25 14:53:16 -05:00
parent d306a06037
commit d7ea381746
1 changed files with 6 additions and 6 deletions
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12
compress.c
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@ -67,7 +67,7 @@ typedef struct {
UT_hash_handle hh;
} tuple_t;
// turn 3 bytes into a single integer for quicker hashing/searching
#define COMBINE(x, y, z) ((x << 16) | (y << 8) | z)
#define COMBINE(w, x, y, z) ((w << 24) | (x << 16) | (y << 8) | z)
uint8_t rotate (uint8_t);
rle_t rle_check (uint8_t*, uint8_t*, uint32_t, int);
@ -101,9 +101,9 @@ size_t pack(uint8_t *unpacked, size_t inputsize, uint8_t *packed, int fast) {
debug("inputsize = %d\n", inputsize);
for (uint16_t i = 0; i < inputsize - 3; i++) {
for (uint16_t i = 0; i < inputsize - 4; i++) {
tuple_t *tuple;
int currbytes = COMBINE(unpacked[i], unpacked[i+1], unpacked[i+2]);
int currbytes = COMBINE(unpacked[i], unpacked[i+1], unpacked[i+2], unpacked[i+3]);
// has this one been indexed already
HASH_FIND_INT(offsets, &currbytes, tuple);
@ -419,7 +419,7 @@ backref_t ref_search (uint8_t *start, uint8_t *current, uint32_t insize, int fas
// references to previous data which goes in the same direction
// see if this byte pair exists elsewhere, then start searching.
currbytes = COMBINE(current[0], current[1], current[2]);
currbytes = COMBINE(current[0], current[1], current[2], current[3]);
HASH_FIND_INT(offsets, &currbytes, tuple);
if (tuple) for (uint8_t *pos = start + tuple->offset; pos < current; pos++) {
// see how many bytes in a row are the same between the current uncompressed data
@ -443,7 +443,7 @@ backref_t ref_search (uint8_t *start, uint8_t *current, uint32_t insize, int fas
// references to data where the bits are rotated
// see if this byte pair exists elsewhere, then start searching.
currbytes = COMBINE(rotate(current[0]), rotate(current[1]), rotate(current[2]));
currbytes = COMBINE(rotate(current[0]), rotate(current[1]), rotate(current[2]), rotate(current[3]));
HASH_FIND_INT(offsets, &currbytes, tuple);
if (tuple) for (uint8_t *pos = start + tuple->offset; pos < current; pos++) {
// now repeat the check with the bit rotation method
@ -463,7 +463,7 @@ backref_t ref_search (uint8_t *start, uint8_t *current, uint32_t insize, int fas
// references to data which goes backwards
// see if this byte pair exists elsewhere, then start searching.
currbytes = COMBINE(current[2], current[1], current[0]);
currbytes = COMBINE(current[3], current[2], current[1], current[0]);
HASH_FIND_INT(offsets, &currbytes, tuple);
// add 2 to offset since we're starting at the end of the 3 byte sequence here
if (tuple) for (uint8_t *pos = start + tuple->offset + 2; pos < current; pos++) {