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Implement atomic_testandclear_{32,int,long} for 32-bit arm. Also, replace

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the existing implementation of atomic_testandset with the same new algorithm,
which uses fewer instructions and fewer registers.
This commit is contained in:
Ian Lepore 2020-02-10 00:05:04 +00:00
parent 6a34ec63ab
commit 39c614c6b7
1 changed files with 66 additions and 14 deletions
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80
sys/arm/include/atomic-v6.h
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@ -858,23 +858,75 @@ atomic_store_rel_long(volatile u_long *p, u_long v)
}
static __inline int
atomic_testandset_32(volatile uint32_t *p, u_int v)
atomic_testandclear_32(volatile uint32_t *ptr, u_int bit)
{
uint32_t tmp, tmp2, res, mask;
int newv, oldv, result;
mask = 1u << (v & 0x1f);
tmp = tmp2 = 0;
__asm __volatile(
"1: ldrex %0, [%4] \n"
" orr %1, %0, %3 \n"
" strex %2, %1, [%4] \n"
" cmp %2, #0 \n"
" it ne \n"
" bne 1b \n"
: "=&r" (res), "=&r" (tmp), "=&r" (tmp2)
: "r" (mask), "r" (p)
: "cc", "memory");
return ((res & mask) != 0);
" mov ip, #1 \n"
" lsl ip, ip, %[bit] \n"
/* Done with %[bit] as input, reuse below as output. */
"1: \n"
" ldrex %[oldv], [%[ptr]] \n"
" bic %[newv], %[oldv], ip \n"
" strex %[bit], %[newv], [%[ptr]] \n"
" teq %[bit], #0 \n"
" it ne \n"
" bne 1b \n"
" ands %[bit], %[oldv], ip \n"
" it ne \n"
" movne %[bit], #1 \n"
: [bit] "=&r" (result),
[oldv] "=&r" (oldv),
[newv] "=&r" (newv)
: [ptr] "r" (ptr),
"[bit]" (bit)
: "cc", "ip", "memory");
return (result);
}
static __inline int
atomic_testandclear_int(volatile u_int *p, u_int v)
{
return (atomic_testandclear_32((volatile uint32_t *)p, v));
}
static __inline int
atomic_testandclear_long(volatile u_long *p, u_int v)
{
return (atomic_testandclear_32((volatile uint32_t *)p, v));
}
static __inline int
atomic_testandset_32(volatile uint32_t *ptr, u_int bit)
{
int newv, oldv, result;
__asm __volatile(
" mov ip, #1 \n"
" lsl ip, ip, %[bit] \n"
/* Done with %[bit] as input, reuse below as output. */
"1: \n"
" ldrex %[oldv], [%[ptr]] \n"
" orr %[newv], %[oldv], ip \n"
" strex %[bit], %[newv], [%[ptr]] \n"
" teq %[bit], #0 \n"
" it ne \n"
" bne 1b \n"
" ands %[bit], %[oldv], ip \n"
" it ne \n"
" movne %[bit], #1 \n"
: [bit] "=&r" (result),
[oldv] "=&r" (oldv),
[newv] "=&r" (newv)
: [ptr] "r" (ptr),
"[bit]" (bit)
: "cc", "ip", "memory");
return (result);
}
static __inline int