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Reduce realloc syscall overhead for FT2232 and bitbang

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FT2232 ran realloc() for every executed command. Start with a big enough
buffer and don't touch buffer size unless it needs to grow.
Bitbang was slightly better: It only ran realloc() if buffer size
changed. Still, the solution above improves performance and reliability.

Corresponding to flashrom svn r780.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Sean Nelson <audiohacked@gmail.com>
This commit is contained in:
Carl-Daniel Hailfinger
2009-11-25 16:58:17 +00:00
parent 2925d6f11d
commit b7e01457d1
2 changed files with 17 additions and 6 deletions
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7
bitbang_spi.c
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@ -87,14 +87,16 @@ int bitbang_spi_send_command(unsigned int writecnt, unsigned int readcnt,
static unsigned char *bufout = NULL;
static unsigned char *bufin = NULL;
static int oldbufsize = 0;
int bufsize = max(writecnt + readcnt, 260);
int bufsize;
int i;
/* Arbitrary size limitation here. We're only constrained by memory. */
if (writecnt > 65536 || readcnt > 65536)
return SPI_INVALID_LENGTH;
if (bufsize != oldbufsize) {
bufsize = max(writecnt + readcnt, 260);
/* Never shrink. realloc() calls are expensive. */
if (bufsize > oldbufsize) {
bufout = realloc(bufout, bufsize);
if (!bufout) {
fprintf(stderr, "Out of memory!\n");
@ -109,6 +111,7 @@ int bitbang_spi_send_command(unsigned int writecnt, unsigned int readcnt,
free(bufout);
exit(1);
}
oldbufsize = bufsize;
}
memcpy(bufout, writearr, writecnt);