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libbb/md5: code shrink

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function                                             old     new   delta
md5_end                                              123     117      -6
md5_begin                                             49      42      -7
md5_hash                                             119     104     -15

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko 2010-10-16 01:08:32 +02:00
parent 3d16098494
commit 70186711f4
2 changed files with 26 additions and 23 deletions
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1
include/libbb.h
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@ -1540,7 +1540,6 @@ typedef struct md5_ctx_t {
uint32_t C;
uint32_t D;
uint64_t total;
uint32_t buflen;
char buffer[128];
} md5_ctx_t;
#else

48
libbb/md5.c
View File

@ -1,7 +1,7 @@
/* vi: set sw=4 ts=4: */
/*
* md5.c - Compute MD5 checksum of strings according to the
* definition of MD5 in RFC 1321 from April 1992.
* Compute MD5 checksum of strings according to the
* definition of MD5 in RFC 1321 from April 1992.
*
* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
*
@ -34,7 +34,6 @@ void FAST_FUNC md5_begin(md5_ctx_t *ctx)
ctx->C = 0x98badcfe;
ctx->D = 0x10325476;
ctx->total = 0;
ctx->buflen = 0;
}
/* These are the four functions used in the four steps of the MD5 algorithm
@ -355,35 +354,39 @@ static void md5_hash_block(const void *buffer, md5_ctx_t *ctx)
ctx->D = D;
}
/* The size of filled part of ctx->buffer: */
#define BUFLEN(ctx) (((unsigned)ctx->total) & 63)
/* Feed data through a temporary buffer to call md5_hash_aligned_block()
* with chunks of data that are 4-byte aligned and a multiple of 64 bytes.
* This function's internal buffer remembers previous data until it has 64
* bytes worth to pass on. Call md5_end() to flush this buffer. */
void FAST_FUNC md5_hash(const void *buffer, size_t len, md5_ctx_t *ctx)
{
char *buf = (char *)buffer;
const char *buf = buffer;
unsigned buflen = BUFLEN(ctx);
/* RFC 1321 specifies the possible length of the file up to 2^64 bits,
/* RFC 1321 specifies the possible length of the file up to 2^64 bits.
* Here we only track the number of bytes. */
ctx->total += len;
/* Process all input. */
while (len) {
unsigned i = 64 - ctx->buflen;
/* Copy data into aligned buffer. */
while (1) {
unsigned i = 64 - buflen;
if (i > len)
i = len;
memcpy(ctx->buffer + ctx->buflen, buf, i);
/* Copy data into aligned buffer. */
memcpy(ctx->buffer + buflen, buf, i);
len -= i;
ctx->buflen += i;
buf += i;
/* When buffer fills up, process it. */
if (ctx->buflen == 64) {
md5_hash_block(ctx->buffer, ctx);
ctx->buflen = 0;
}
buflen += i;
/* clever way to do "if (buflen != 64) break; ... ; buflen = 0;" */
buflen -= 64;
if (buflen != 0)
break;
/* Buffer is filled up, process it. */
md5_hash_block(ctx->buffer, ctx);
/*buflen = 0; - already is */
}
}
@ -396,18 +399,19 @@ void FAST_FUNC md5_end(void *resbuf, md5_ctx_t *ctx)
{
uint64_t total;
char *buf = ctx->buffer;
int i;
unsigned i;
unsigned buflen = BUFLEN(ctx);
/* Pad data to block size. */
buf[ctx->buflen++] = 0x80;
memset(buf + ctx->buflen, 0, 128 - ctx->buflen);
buf[buflen++] = 0x80;
memset(buf + buflen, 0, 128 - buflen);
/* Put the 64-bit file length, expressed in *bits*,
* at the end of the buffer.
*/
/* clever way to do "if (buflen > 56) buf += 64": */
buf += ((buflen + 7) & 64);
total = ctx->total << 3;
if (ctx->buflen > 56)
buf += 64;
for (i = 0; i < 8; i++) {
buf[56 + i] = total;
total >>= 8;