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Use as much of the low buffer as possible with a single memcopy before going fine grained byte by byte.

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Con Kolivas 2012-03-08 09:01:31 +11:00
parent 30bfe06f1a
commit cf8567e314
1 changed files with 9 additions and 6 deletions
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15
rzip.c
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@ -190,7 +190,7 @@ static uchar *single_get_sb(__maybe_unused rzip_control *control, struct sliding
/* Since the sliding get_sb only allows us to access one byte at a time, we
* do the same as we did with get_sb with the memcpy since one memcpy is much
* faster than numerous memcpys 1 byte at a time */
static void single_mcpy(__maybe_unused rzip_control *control, unsigned char *buf, i64 offset, i64 len)
static void single_mcpy(rzip_control *control, unsigned char *buf, i64 offset, i64 len)
{
memcpy(buf, control->sb.buf_low + offset, len);
}
@ -198,16 +198,19 @@ static void single_mcpy(__maybe_unused rzip_control *control, unsigned char *buf
static void sliding_mcpy(rzip_control *control, unsigned char *buf, i64 offset, i64 len)
{
struct sliding_buffer *sb = &control->sb;
i64 i;
i64 i, offdiff = offset - sb->offset_low;
/* See if we fit in the low buffer first and use the faster function
* where possible */
if (offset >= sb->offset_low && offset + len < sb->offset_low + sb->size_low) {
single_mcpy(control, buf, offset - sb->offset_low, len);
return;
if (offdiff >= 0 && offdiff < sb->size_low) {
i64 minlen = MIN(len, sb->size_low - offdiff);
memcpy(buf, control->sb.buf_low + offdiff, minlen);
len -= minlen;
}
/* We have no choice but to go fine-grained since we will be paging */
/* We have no choice but to go fine-grained if there's any len left
* since we will be paging */
for (i = 0; i < len; i++)
memcpy(buf + i, sliding_get_sb(control, &control->sb, offset + i), 1);
}