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micro-optimization: avoid one API call in 'read_chars'

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This commit is contained in:
Roberto Ierusalimschy 2008-02-12 15:05:36 -02:00
parent 7f69f0efb0
commit f86f4116c8
1 changed files with 11 additions and 10 deletions
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21
liolib.c
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@ -1,5 +1,5 @@
/*
** $Id: liolib.c,v 2.77 2007/12/08 11:54:32 roberto Exp roberto $
** $Id: liolib.c,v 2.78 2008/02/12 16:51:03 roberto Exp roberto $
** Standard I/O (and system) library
** See Copyright Notice in lua.h
*/
@ -310,20 +310,21 @@ static int read_line (lua_State *L, FILE *f) {
static int read_chars (lua_State *L, FILE *f, size_t n) {
size_t rlen; /* how much to read */
size_t nr; /* number of chars actually read */
size_t tbr = n; /* number of chars to be read */
size_t rlen; /* how much to read in each cycle */
size_t nr; /* number of chars actually read in each cycle */
luaL_Buffer b;
luaL_buffinit(L, &b);
rlen = LUAL_BUFFERSIZE; /* try to read that much each time */
do {
char *p = luaL_prepbuffer(&b);
if (rlen > n) rlen = n; /* cannot read more than asked */
if (rlen > tbr) rlen = tbr; /* cannot read more than asked */
nr = fread(p, sizeof(char), rlen, f);
luaL_addsize(&b, nr);
n -= nr; /* still have to read `n' chars */
} while (n > 0 && nr == rlen); /* until end of count or eof */
tbr -= nr; /* still have to read 'tbr' chars */
} while (tbr > 0 && nr == rlen); /* until end of count or eof */
luaL_pushresult(&b); /* close buffer */
return (lua_objlen(L, -1) > 0);
return (tbr < n); /* true iff read something */
}
@ -386,13 +387,13 @@ static int f_read (lua_State *L) {
static int io_readline (lua_State *L) {
FILE *f = *(FILE **)lua_touserdata(L, lua_upvalueindex(1));
int sucess;
int success;
if (f == NULL) /* file is already closed? */
luaL_error(L, "file is already closed");
sucess = read_line(L, f);
success = read_line(L, f);
if (ferror(f))
return luaL_error(L, "%s", strerror(errno));
if (sucess) return 1;
if (success) return 1;
else { /* EOF */
if (lua_toboolean(L, lua_upvalueindex(2))) { /* generator created file? */
lua_settop(L, 0);