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// +build sse
// +build amd64
#include "textflag.h"
// func divAsm(a, b []float64)
TEXT ·divAsm(SB), NOSPLIT, $0
MOVQ a_data+0(FP), SI
MOVQ b_data+24(FP), DI // use destination index register for this
MOVQ a_len+8(FP), AX // len(a) into AX
// check if there are at least 8 elements
SUBQ $8, AX
JL remainder
loop:
// a[0]
MOVAPD (SI), X0
MOVAPD (DI), X1
DIVPD X1, X0
MOVAPD X0, (SI)
MOVAPD 16(SI), X2
MOVAPD 16(DI), X3
DIVPD X3, X2
MOVAPD X2, 16(SI)
MOVAPD 32(SI), X4
MOVAPD 32(DI), X5
DIVPD X5, X4
MOVAPD X4, 32(SI)
MOVAPD 48(SI), X6
MOVAPD 48(DI), X7
DIVPD X7, X6
MOVAPD X6, 48(SI)
// update pointers. 4 registers, 2 elements each, 8 bytes per element
ADDQ $64, SI
ADDQ $64, DI
// len(a) is now 4*2 elements less
SUBQ $8, AX
JGE loop
remainder:
ADDQ $8, AX
JE done
remainderloop:
// copy into the appropriate registers
MOVSD (SI), X0
MOVSD (DI), X1
DIVSD X1, X0
// save it back
MOVSD X0, (SI)
// update pointer to the top of the data
ADDQ $8, SI
ADDQ $8, DI
DECQ AX
JNE remainderloop
done:
RET
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