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chan: allocate a new chan with one

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malloc rather than nelements + 1.

R=rob
CC=golang-dev
https://golang.org/cl/4291064
This commit is contained in:
Ken Thompson 2011-03-22 18:41:17 -07:00
parent 005fe41125
commit a73817716a
1 changed files with 20 additions and 4 deletions
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24
src/pkg/runtime/chan.c
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@ -5,6 +5,8 @@
#include "runtime.h"
#include "type.h"
#define MAXALIGN 7
static int32 debug = 0;
typedef struct Link Link;
@ -95,7 +97,9 @@ Hchan*
runtime·makechan_c(Type *elem, int64 hint)
{
Hchan *c;
int32 i;
int32 i, m, n;
Link *d, *b, *e;
byte *by;
if(hint < 0 || (int32)hint != hint || hint > ((uintptr)-1) / elem->size)
runtime·panicstring("makechan: size out of range");
@ -105,7 +109,19 @@ runtime·makechan_c(Type *elem, int64 hint)
runtime·throw("runtime.makechan: unsupported elem type");
}
c = runtime·mal(sizeof(*c));
// calculate rounded sizes of Hchan and Link
n = sizeof(*c);
while(n & MAXALIGN)
n++;
m = sizeof(*d) + elem->size - sizeof(d->elem);
while(m & MAXALIGN)
m++;
// allocate memory in one call
by = runtime·mal(n + hint*m);
c = (Hchan*)by;
by += n;
runtime·addfinalizer(c, destroychan, 0);
c->elemsize = elem->size;
@ -113,13 +129,13 @@ runtime·makechan_c(Type *elem, int64 hint)
c->elemalign = elem->align;
if(hint > 0) {
Link *d, *b, *e;
// make a circular q
b = nil;
e = nil;
for(i=0; i<hint; i++) {
d = runtime·mal(sizeof(*d) + c->elemsize - sizeof(d->elem));
d = (Link*)by;
by += m;
if(e == nil)
e = d;
d->link = b;