?? ppc_fdiv.s
字號:
cmpwi cr7,r12,0 /* set fpb.sign */
rlwinm. r9,r9,0,0x000fffff /* isolate fpa.hi */
SAVEREG(17) /* save r17 */
cror cr6_zero,cr0_2,cr0_2 /* fpa.zero = fpa.hi == 0 */
rlwinm. r12,r12,0,0x000fffff /* isolate fpb.hi */
SAVEREG(18) /* save r18 */
cror cr7_zero,cr0_2,cr0_2 /* fpb.zero = fpa.hi == 0 */
cmpwi cr0,r10,0 /* if (fpa.lo == 0) */
SAVEREG(19) /* save r19 */
crand cr6_zero,cr6_zero,cr0_2 /* fpa.zero = fpa.hi==0 && fpa.lo==0 */
cmpwi cr0,r6,0 /* if (fpa.lo == 0) */
SAVEREG(20) /* save r20 */
crand cr7_zero,cr7_zero,cr0_2 /* fpb.zero = fpb.hi==0 && fpb.lo==0 */
cmpwi cr2,r8,0x7ff /* if (fpa.exp == DEXPMAX) */
SAVEREG(21) /* save r21 */
SAVEREG(22) /* save r22 */
cmpwi cr0,r8,0 /* if (fpa.exp == 0) */
SAVEREG(23) /* save r23 */
crand cr6_zero,cr6_zero,cr0_2 /* fpa.zero=(fpa.exp==0 && fpa==0) */
SAVEREG(24) /* save r24 */
crandc cr0_2,cr0_2,cr6_zero /* if (fpa.exp==0 && fpa!=0) */
cmpwi cr3,r11,0x7ff /* if (fpb.exp == DEXPMAX) */
beq+ denormal_a /* { Add implied 1 to significand */
oris r9,r9,0x0010 /* fpa.hi |= 0x00100000; */
b adone /* } else { */
denormal_a:
addi r8,r8,1 /* fpa.exp++; */
adone: /* } */
SAVEREG(25) /* save r25 */
cmpwi cr0,r11,0 /* if (fpb.exp == 0) */
SAVEREG(26) /* save r26 */
crand cr7_zero,cr7_zero,cr0_2 /* fpb.zero=(fpb.exp==0 && fpb==0) */
SAVEREG(27) /* save r27 */
crandc cr0_2,cr0_2,cr7_zero /* if (fpb.exp==0 && fpb!=0) */
SAVEREG(28) /* save r28 */
beq+ denormal_b /* { Add implied 1 to significand */
oris r12,r12,0x0010 /* fpb.hi |= 0x00100000; */
b bdone /* } else { */
denormal_b:
addi r11,r11,1 /* fpb.exp++; */
bdone: /* } */
bt cr2_2,a_INForNaN /* if (fpa.exp == 0x7ff) goto a_INForNaN; */
bt cr3_2,b_INForNaN /* if (fpb.exp == 0x7ff) goto b_INForNaN; */
bt cr6_zero,a_zero /* if (fpa.zero) goto a_zero; */
bt cr7_zero,b_zero /* if (fpb.zero) goto b_zero; */
SAVEREG(29) /* save r29 */
/* force divisor to be normalized */
cntlzw r7,r12 /* s = cntlz(fpb.hi); */
cmpwi cr0,r7,11 /* if (s > 11) */
SAVEREG(30) /* save r30 */
SAVEREG(31) /* save r31 */
ble drdone /* { */
cmpwi cr0,r7,32 /* if (s < 32) */
addi r7,r7,-11 /* r6 = s-11; */
subfic r5,r7,32 /* r5 = 43-s; */
bge bshgt32 /* { */
subf r11,r7,r11 /* fpb.exp -= (s-11); */
slw r12,r12,r7 /* fpb.hi <<= s-11; */
srw r0,r6,r5 /* temp = fpa.lo >> 43-s; */
or r12,r12,r0 /* fpb.hi |= temp; */
slw r6,r6,r7 /* fpb.lo <<= s-11; */
b drdone /* } */
bshgt32: /* else */
/* { */
addi r11,r11,-32 /* fpb.exp -= 32; */
cntlzw r7,r6 /* s = cntlz(fpb.lo); */
cmpwi cr0,r7,11 /* if (s >= 11) */
blt bshgt43 /* { */
addi r7,r7,-11 /* r6 = s-11; */
subf r11,r7,r11 /* fpb.exp -= (s-11); */
slw r12,r6,r7 /* fpb.hi = fpb.lo << s-11; */
addi r6,0,0 /* fpb.lo = 0; */
b drdone /* } */
bshgt43: /* else */
/* { */
subfic r7,r7,11 /* r6 = 11-s; */
add r11,r7,r11 /* fpb.exp += (11-s); */
srw r12,r6,r7 /* fpb.hi = fpb.lo >> 11-s; */
subfic r5,r7,32 /* r5 = 21+s; */
slw r6,r6,r5 /* fpb.lo << (21+s); */
/* } */
/* } */
drdone: /* } */
/* right justify a 16 bit divisor */
rlwinm r7,r12,32-5,0x0000ffff /* dr = fpb.hi >> 5; */
/* Calculate sign */
crxor cr6_sign,cr6_sign,cr7_sign
/* set up for loop */
crset first_loop /* first_loop = true; */
addi r0,0,4 /* r0 = 4; */
mtctr r0 /* ctr = 4; */
addi r31,0,0 /* t.save = 0; */
do_divide: /* for (nest=0;nest<5;nest++) { */
/* force dividend to be normalized */
cntlzw r28,r9 /* s = cntlz(fpa.hi); */
cmpwi cr0,r28,11 /* if (s > 11) */
ble dddone /* { */
cmpwi cr0,r28,32 /* if (s < 32) */
addi r28,r28,-11 /* r28 = s-11; */
subfic r5,r28,32 /* r5 = 43-s; */
bge ashgt32 /* { */
subf r8,r28,r8 /* fpa.exp -= (s-11); */
slw r9,r9,r28 /* fpa.hi <<= s-11; */
srw r0,r10,r5 /* temp = fpa.lo >> 43-s; */
or r9,r9,r0 /* fpa.hi |= temp; */
slw r10,r10,r28 /* fpa.lo <<= s-11; */
srw r0,r31,r5 /* temp = r.save >> 43-s; */
or r10,r10,r0 /* fpa.lo |= temp; */
b dddone /* } */
ashgt32: /* else */
/* { */
addi r8,r8,-32 /* fpa.exp -= 32; */
cntlzw r28,r10 /* s = cntlz(fpa.lo); */
cmpwi cr0,r28,11 /* if (s >= 11) */
blt ashgt43 /* { */
addi r28,r28,-11 /* r28 = s-11; */
subf r8,r28,r8 /* fpa.exp -= (s-11); */
slw r9,r10,r28 /* fpa.hi = fpa.lo << s-11; */
subfic r5,r28,32 /* r5 = 43-s; */
srw r0,r31,r5 /* temp = t.save >> 43-s; */
or r9,r9,r0 /* fpa.hi |= temp; */
slw r10,r31,r28 /* fpa.lo = t.save << s-11; */
b dddone /* } */
ashgt43: /* else */
/* { */
subfic r28,r28,11 /* r28 = 11-s; */
add r8,r28,r8 /* fpa.exp += (11-s); */
srw r9,r10,r28 /* fpa.hi = fpa.lo >> 11-s; */
subfic r5,r28,32 /* r5 = 21+s; */
slw r10,r10,r5 /* fpa.lo << (21+s); */
srw r0,r31,r28 /* temp = tsave >> 11-s; */
or r10,r10,r0 /* fpa.lo |= temp; */
/* } */
/* } */
dddone: /* } */
/* left justify dividend */
rlwinm r5,r9,11,0xfffff800 /* dd = fpa.hi << 11; */
rlwimi r5,r10,11,0x000007ff /* dd |= fpa.lo >> 21; */
/* estimate quotient (truncate to 16 bits) */
divwu r27,r5,r7 /* e.hi = dd/dr; */
cntlzw r28,r27 /* s = cntlz(e.hi); */
addi r26,r8,1023+15 /* e.exp = fpa.exp + DEXPBIAS+15; */
subf r26,r11,r26 /* e.exp -= fpb.exp; */
subf r26,r28,r26 /* e.exp -= s; */
addi r28,r28,-11 /* r28 = s-11; */
rlwnm r27,r27,r28,0x001fffe0 /* e.hi = (e.hi << s-11) & 0x001fffe0; */
eshdone:
/* t (temporary) = b (divisor) * e (estimate) */
/* Multiply b-low and e */
mulhwu r24,r6,r27 /* r24,r25 = fpb.lo * e; */
mullw r25,r6,r27
/* r29,r30,r31 = r24,r25 >> 20 */
rlwinm r29,r24,32-20,0xfff /* r29 = r24 >> 20; */
rlwinm r30,r24,12,0xfffff000 /* r30 = r24 << 12; */
rlwimi r30,r25,32-20,0xfff /* r30 += (r25>>20)&0xfff; */
rlwinm r31,r25,12,0xfffff000 /* r31 = r25 << 12; */
/* Multiply b-high and e */
mulhwu r24,r12,r27 /* r24,r25 = fpb.hi * e; */
mullw r25,r12,r27
/* r21,r22 = r24,r25 << 12 */
rlwinm r21,r24,12,0xfffff000 /* t.hi = r24 << 12; */
rlwimi r21,r25,32-20,0xfff /* t.hi += ((r25>>20)&0xfff); */
rlwinm r22,r25,12,0xfffff000 /* t.lo = r25 << 12; */
/* r21,r22,r31 += r29,r30,r31 */
addc r22,r22,r30 /* t.lo += r30; */
adde r21,r21,r29 /* t.hi += r29 + (CA); */
add r20,r11,r26 /* t.exp = fpb.exp + e.exp; */
addi r20,r20,-1023 /* t.exp -= DEXPBIAS; */
/* r (remainder) = a (dividend) - t (temporary) */
cmpw cr0,r20,r8 /* if (t.exp < fpa.exp) */
subf r28,r20,r8 /* shift = fpa.exp - t.exp; */
subfic r5,r28,32 /* r5 = 32-shift; */
bge+ tnoshift /* { */
srw r31,r31,r28 /* t.save >> shift; */
slw r0,r22,r5 /* temp = t.lo << (32-shift); */
or r31,r31,r0 /* t.save |= temp; */
srw r22,r22,r28 /* t.lo >>= shift; */
slw r0,r21,r5 /* temp = t.hi << (shift-32); */
or r22,r22,r0 /* t.lo |= temp; */
srw r21,r21,r28 /* t.hi >>= shift; */
tnoshift: /* } */
subfic r31,r31,0 /* t = -t; */
subfze r22,r22
subfze r21,r21
do_rem:
adde r25,r22,r10 /* r.lo = fpa.lo + t.lo; */
adde. r24,r21,r9 /* r.hi = fpa.hi + t.hi; */
subf r20,r26,r17 /* shift = c.exp - e.exp; */
bge+ addinq /* if (r.hi >= 0) { */
addi r27,r27,-32 /* e.hi -= 32; */
b eshdone
addinq: /* } */
/* c (quotient) += e (estimate) */
bt first_loop,first /* if (first_loop) { */
cmpwi cr0,r20,32 /* if (shift < 32) */
subfic r21,r20,32 /* r21 = 32-shift; */
addi r0,0,0 /* round = 0; */
bge shgt32 /* { */
slw r28,r27,r21 /* e.lo = e.hi << (32-shift); */
srw r27,r27,r20 /* e.hi >>= shift; */
b addit /* } */
shgt32: /* else */
/* { */
cmpwi cr0,r20,64 /* if (shift => 64) */
addi r20,r20,-32 /* shift -= 32; */
subfic r21,r20,32 /* r21 = 32-shift; */
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