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use copy loops instead of memcpy/memmove

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because different versions of gcc seem to disagree on how both of these
functions should handle overlapping memory. thanks stallman
This commit is contained in:
devinacker 2013-10-26 14:41:21 -04:00
parent e8fb851b50
commit f8ed01c458
1 changed files with 53 additions and 51 deletions
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104
compress.c
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@ -158,6 +158,8 @@ size_t unpack(uint8_t *packed, uint8_t *unpacked) {
switch (command) {
// write uncompressed bytes
// (note: i had to go back to using loops for all of these because memcpy/memmove
// were both fucking up and handling these inconsistently between versions of gcc)
case 0:
memcpy(&unpacked[outpos], &packed[inpos], length);
@ -166,30 +168,30 @@ size_t unpack(uint8_t *packed, uint8_t *unpacked) {
break;
// 8-bit RLE
case 1:
unpacked[outpos] = packed[inpos++];
memcpy(&unpacked[outpos + 1], &unpacked[outpos], length - 1);
outpos += length;
break;
// 16-bit RLE
case 2:
unpacked[outpos] = packed[inpos];
unpacked[outpos + 1] = packed[inpos + 1];
memcpy(&unpacked[outpos + 2], &unpacked[outpos], 2 * (length - 1));
outpos += (length * 2);
inpos += 2;
break;
// 8-bit increasing sequence
case 3:
for (int i = 0; i < length; i++)
unpacked[outpos++] = packed[inpos] + i;
inpos++;
break;
case 1:
for (int i = 0; i < length; i++)
unpacked[outpos++] = packed[inpos];
inpos++;
break;
// 16-bit RLE
case 2:
for (int i = 0; i < length; i++) {
unpacked[outpos++] = packed[inpos];
unpacked[outpos++] = packed[inpos+1];
}
inpos += 2;
break;
// 8-bit increasing sequence
case 3:
for (int i = 0; i < length; i++)
unpacked[outpos++] = packed[inpos] + i;
inpos++;
break;
// regular backref
// (offset is big-endian)
@ -198,33 +200,33 @@ size_t unpack(uint8_t *packed, uint8_t *unpacked) {
// 7 isn't a real method number, but it behaves the same as 4 due to a quirk in how
// the original decompression routine is programmed. (one of Parasyte's docs confirms
// this for GB games as well). let's handle it anyway
command = 4;
offset = (packed[inpos] << 8) | packed[inpos+1];
memcpy(&unpacked[outpos], &unpacked[offset], length);
outpos += length;
inpos += 2;
break;
// backref with bit rotation
// (offset is big-endian)
case 5:
offset = (packed[inpos] << 8) | packed[inpos+1];
for (int i = 0; i < length; i++)
unpacked[outpos++] = rotate(unpacked[offset + i]);
inpos += 2;
break;
// backwards backref
// (offset is big-endian)
case 6:
offset = (packed[inpos] << 8) | packed[inpos+1];
for (int i = 0; i < length; i++)
unpacked[outpos++] = unpacked[offset - i];
inpos += 2;
command = 4;
offset = (packed[inpos] << 8) | packed[inpos+1];
for (int i = 0; i < length; i++)
unpacked[outpos++] = unpacked[offset + i];
inpos += 2;
break;
// backref with bit rotation
// (offset is big-endian)
case 5:
offset = (packed[inpos] << 8) | packed[inpos+1];
for (int i = 0; i < length; i++)
unpacked[outpos++] = rotate(unpacked[offset + i]);
inpos += 2;
break;
// backwards backref
// (offset is big-endian)
case 6:
offset = (packed[inpos] << 8) | packed[inpos+1];
for (int i = 0; i < length; i++)
unpacked[outpos++] = unpacked[offset - i];
inpos += 2;
}
// keep track of how many times each compression method is used