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hexedit: optimize output buffering

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function                                             old     new   delta
hexedit_main                                         970     998     +28

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2017-09-14 00:04:16 +02:00
parent 62643017c3
commit d72e804e6d
1 changed files with 12 additions and 7 deletions
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19
miscutils/hexedit.c
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@ -38,8 +38,8 @@ struct globals {
/* Hopefully there aren't arches with PAGE_SIZE > 64k */ /* Hopefully there aren't arches with PAGE_SIZE > 64k */
#define G_mapsize (64*1024) #define G_mapsize (64*1024)
/* "12ef5670 (nn )*16 abcdef_1_3_5_7_9\n" */ /* "12ef5670 (xx )*16 _1_3_5_7_9abcdef\n"NUL */
#define LINEBUF_SIZE (8 + 1 + 3*16 + 16 + 1 /*paranoia:*/ + 14) #define LINEBUF_SIZE (8 + 1 + 3*16 + 16 + 1 + 1 /*paranoia:*/ + 13)
static int format_line(char *hex, uint8_t *data, off_t offset) static int format_line(char *hex, uint8_t *data, off_t offset)
{ {
@ -165,7 +165,7 @@ static void move_mapping_further(void)
pagesize = getpagesize(); /* constant on most arches */ pagesize = getpagesize(); /* constant on most arches */
pos = G.current_byte - G.addr; pos = G.current_byte - G.addr;
if (pos >= pagesize) { if (pos >= pagesize) {
/* Move offset up until current position is in 1st page */ /* move offset up until current position is in 1st page */
do { do {
G.offset += pagesize; G.offset += pagesize;
if (G.offset == 0) { /* whoops */ if (G.offset == 0) { /* whoops */
@ -188,7 +188,7 @@ static void move_mapping_lower(void)
pagesize = getpagesize(); /* constant on most arches */ pagesize = getpagesize(); /* constant on most arches */
pos = G.current_byte - G.addr; pos = G.current_byte - G.addr;
/* Move offset down until current position is in last page */ /* move offset down until current position is in last page */
pos += pagesize; pos += pagesize;
while (pos < G_mapsize) { while (pos < G_mapsize) {
pos += pagesize; pos += pagesize;
@ -218,10 +218,15 @@ int hexedit_main(int argc UNUSED_PARAM, char **argv)
INIT_G(); INIT_G();
getopt32(argv, "");
argv += optind;
get_terminal_width_height(-1, NULL, &G.height); get_terminal_width_height(-1, NULL, &G.height);
if (1) {
/* reduce number of write() syscalls while PgUp/Down: fully buffered output */
unsigned sz = (G.height | 0xf) * LINEBUF_SIZE;
setvbuf(stdout, xmalloc(sz), _IOFBF, sz);
}
getopt32(argv, "^" "" "\0" "=1"/*one arg*/);
argv += optind;
G.fd = xopen(*argv, O_RDWR); G.fd = xopen(*argv, O_RDWR);
G.size = xlseek(G.fd, 0, SEEK_END); G.size = xlseek(G.fd, 0, SEEK_END);