mirror of
https://github.com/9fans/plan9port.git
synced 2025-01-15 11:20:03 +00:00
912fba95e7
which were completely bogus. (Libthread used to ignore them but not anymore. Maybe we really should ignore them, but that breaks Venti, which needs *really* big stacks.)
42 lines
947 B
C
42 lines
947 B
C
#include "u.h"
|
|
#include "libc.h"
|
|
|
|
/*
|
|
* first argument (l) is in r3 at entry.
|
|
* r3 contains return value upon return.
|
|
*/
|
|
int
|
|
_tas(int *x)
|
|
{
|
|
int v;
|
|
/*
|
|
* this __asm__ works with gcc 2.95.2 (mac os x 10.1).
|
|
* this assembly language destroys r0 (0), some other register (v),
|
|
* r4 (x) and r5 (temp).
|
|
*/
|
|
__asm__("\n sync\n"
|
|
" li r0,0\n"
|
|
" mr r4,%1 /* &l->val */\n"
|
|
" lis r5,0xdead /* assemble constant 0xdeaddead */\n"
|
|
" ori r5,r5,0xdead /* \" */\n"
|
|
"tas1:\n"
|
|
" dcbf r4,r0 /* cache flush; \"fix for 603x bug\" */\n"
|
|
" lwarx %0,r4,r0 /* v = l->val with reservation */\n"
|
|
" cmp cr0,0,%0,r0 /* v == 0 */\n"
|
|
" bne tas0\n"
|
|
" stwcx. r5,r4,r0 /* if (l->val same) l->val = 0xdeaddead */\n"
|
|
" bne tas1\n"
|
|
"tas0:\n"
|
|
" sync\n"
|
|
" isync\n"
|
|
: "=r" (v)
|
|
: "r" (x)
|
|
: "cc", "memory", "r0", "r4", "r5"
|
|
);
|
|
switch(v) {
|
|
case 0: return 0;
|
|
case 0xdeaddead: return 1;
|
|
default: fprint(2, "tas: corrupted 0x%lux\n", v);
|
|
}
|
|
return 0;
|
|
}
|