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| // Copyright 2012 The Go Authors. All rights reserved.
| // Use of this source code is governed by a BSD-style
| // license that can be found in the LICENSE file.
|
| #include "textflag.h"
|
| #define Big 0x4330000000000000 // 2**52
|
| // func Floor(x float64) float64
| TEXT ·Floor(SB),NOSPLIT,$0
| MOVQ x+0(FP), AX
| MOVQ $~(1<<63), DX // sign bit mask
| ANDQ AX,DX // DX = |x|
| SUBQ $1,DX
| MOVQ $(Big - 1), CX // if |x| >= 2**52-1 or IsNaN(x) or |x| == 0, return x
| CMPQ DX,CX
| JAE isBig_floor
| MOVQ AX, X0 // X0 = x
| CVTTSD2SQ X0, AX
| CVTSQ2SD AX, X1 // X1 = float(int(x))
| CMPSD X1, X0, 1 // compare LT; X0 = 0xffffffffffffffff or 0
| MOVSD $(-1.0), X2
| ANDPD X2, X0 // if x < float(int(x)) {X0 = -1} else {X0 = 0}
| ADDSD X1, X0
| MOVSD X0, ret+8(FP)
| RET
| isBig_floor:
| MOVQ AX, ret+8(FP) // return x
| RET
|
| // func Ceil(x float64) float64
| TEXT ·Ceil(SB),NOSPLIT,$0
| MOVQ x+0(FP), AX
| MOVQ $~(1<<63), DX // sign bit mask
| MOVQ AX, BX // BX = copy of x
| ANDQ DX, BX // BX = |x|
| MOVQ $Big, CX // if |x| >= 2**52 or IsNaN(x), return x
| CMPQ BX, CX
| JAE isBig_ceil
| MOVQ AX, X0 // X0 = x
| MOVQ DX, X2 // X2 = sign bit mask
| CVTTSD2SQ X0, AX
| ANDNPD X0, X2 // X2 = sign
| CVTSQ2SD AX, X1 // X1 = float(int(x))
| CMPSD X1, X0, 2 // compare LE; X0 = 0xffffffffffffffff or 0
| ORPD X2, X1 // if X1 = 0.0, incorporate sign
| MOVSD $1.0, X3
| ANDNPD X3, X0
| ORPD X2, X0 // if float(int(x)) <= x {X0 = 1} else {X0 = -0}
| ADDSD X1, X0
| MOVSD X0, ret+8(FP)
| RET
| isBig_ceil:
| MOVQ AX, ret+8(FP)
| RET
|
| // func Trunc(x float64) float64
| TEXT ·Trunc(SB),NOSPLIT,$0
| MOVQ x+0(FP), AX
| MOVQ $~(1<<63), DX // sign bit mask
| MOVQ AX, BX // BX = copy of x
| ANDQ DX, BX // BX = |x|
| MOVQ $Big, CX // if |x| >= 2**52 or IsNaN(x), return x
| CMPQ BX, CX
| JAE isBig_trunc
| MOVQ AX, X0
| MOVQ DX, X2 // X2 = sign bit mask
| CVTTSD2SQ X0, AX
| ANDNPD X0, X2 // X2 = sign
| CVTSQ2SD AX, X0 // X0 = float(int(x))
| ORPD X2, X0 // if X0 = 0.0, incorporate sign
| MOVSD X0, ret+8(FP)
| RET
| isBig_trunc:
| MOVQ AX, ret+8(FP) // return x
| RET
|
|
