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38fd0721d0
When a reference buffer is used multiple times then its index can be computed only once and reused multiple times. This patch adds an extra pointer to a pointer argument (from_index) to diff_delta() for this. If from_index is NULL then everything is like before. If from_index is non NULL and *from_index is NULL then the index is created and its location stored to *from_index. In this case the caller has the responsibility to free the memory pointed to by *from_index. If from_index and *from_index are non NULL then the index is reused as is. This currently saves about 10% of CPU time to repack the git archive. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
35 lines
903 B
C
35 lines
903 B
C
#ifndef DELTA_H
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#define DELTA_H
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/* handling of delta buffers */
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extern void *diff_delta(void *from_buf, unsigned long from_size,
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void *to_buf, unsigned long to_size,
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unsigned long *delta_size, unsigned long max_size);
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extern void *patch_delta(void *src_buf, unsigned long src_size,
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void *delta_buf, unsigned long delta_size,
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unsigned long *dst_size);
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/* the smallest possible delta size is 4 bytes */
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#define DELTA_SIZE_MIN 4
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/*
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* This must be called twice on the delta data buffer, first to get the
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* expected reference buffer size, and again to get the result buffer size.
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*/
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static inline unsigned long get_delta_hdr_size(const unsigned char **datap)
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{
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const unsigned char *data = *datap;
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unsigned char cmd;
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unsigned long size = 0;
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int i = 0;
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do {
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cmd = *data++;
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size |= (cmd & ~0x80) << i;
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i += 7;
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} while (cmd & 0x80);
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*datap = data;
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return size;
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}
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#endif
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