floor_riscv64.s

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  #include "textflag.h"
     6  
     7  #define PosInf 0x7FF0000000000000
     8  
     9  // The rounding mode of RISC-V is different from Go spec.
    10  
    11  #define ROUNDFN(NAME, MODE) 	\
    12  TEXT NAME(SB),NOSPLIT,$0; 	\
    13  	MOVD	x+0(FP), F0; 	\
    14  	/* whether x is NaN */; \
    15  	FEQD	F0, F0, X6;	\
    16  	BNEZ	X6, 3(PC);	\
    17  	/* return NaN if x is NaN */; \
    18  	MOVD	F0, ret+8(FP); 	\
    19  	RET;			\
    20  	MOV	$PosInf, X6;	\
    21  	FMVDX	X6, F1;		\
    22  	FABSD	F0, F2;		\
    23  	/* if abs(x) > +Inf, return Inf instead of round(x) */; \
    24  	FLTD	F1, F2, X6;	\
    25  	/* Inf should keep same signed with x then return */;	\
    26  	BEQZ	X6, 3(PC); \
    27  	FCVTLD.MODE	F0, X6;	\
    28  	FCVTDL	X6, F1;		\
    29  	/* rounding will drop signed bit in RISCV, restore it */; \
    30  	FSGNJD	F0, F1, F0;	\
    31  	MOVD	F0, ret+8(FP); 	\
    32  	RET
    33  
    34  // func archFloor(x float64) float64
    35  ROUNDFN(·archFloor, RDN)
    36  
    37  // func archCeil(x float64) float64
    38  ROUNDFN(·archCeil, RUP)
    39  
    40  // func archTrunc(x float64) float64
    41  ROUNDFN(·archTrunc, RTZ)
    42
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