xref: /openbsd-src/gnu/llvm/compiler-rt/lib/builtins/arm/modsi3.S (revision 3cab2bb3f667058bece8e38b12449a63a9d73c4b)
1*3cab2bb3Spatrick//===-- modsi3.S - 32-bit signed integer modulus --------------------------===//
2*3cab2bb3Spatrick//
3*3cab2bb3Spatrick// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*3cab2bb3Spatrick// See https://llvm.org/LICENSE.txt for license information.
5*3cab2bb3Spatrick// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*3cab2bb3Spatrick//
7*3cab2bb3Spatrick//===----------------------------------------------------------------------===//
8*3cab2bb3Spatrick//
9*3cab2bb3Spatrick// This file implements the __modsi3 (32-bit signed integer modulus) function
10*3cab2bb3Spatrick// for the ARM architecture as a wrapper around the unsigned routine.
11*3cab2bb3Spatrick//
12*3cab2bb3Spatrick//===----------------------------------------------------------------------===//
13*3cab2bb3Spatrick
14*3cab2bb3Spatrick#include "../assembly.h"
15*3cab2bb3Spatrick
16*3cab2bb3Spatrick#define ESTABLISH_FRAME \
17*3cab2bb3Spatrick    push   {r4, r7, lr}    ;\
18*3cab2bb3Spatrick    add     r7,     sp, #4
19*3cab2bb3Spatrick#define CLEAR_FRAME_AND_RETURN \
20*3cab2bb3Spatrick    pop    {r4, r7, pc}
21*3cab2bb3Spatrick
22*3cab2bb3Spatrick	.syntax unified
23*3cab2bb3Spatrick	.text
24*3cab2bb3Spatrick	DEFINE_CODE_STATE
25*3cab2bb3Spatrick
26*3cab2bb3Spatrick@ int __modsi3(int divident, int divisor)
27*3cab2bb3Spatrick@   Calculate and return the remainder of the (signed) division.
28*3cab2bb3Spatrick
29*3cab2bb3Spatrick	.p2align 3
30*3cab2bb3SpatrickDEFINE_COMPILERRT_FUNCTION(__modsi3)
31*3cab2bb3Spatrick#if __ARM_ARCH_EXT_IDIV__
32*3cab2bb3Spatrick	tst     r1, r1
33*3cab2bb3Spatrick	beq     LOCAL_LABEL(divzero)
34*3cab2bb3Spatrick	sdiv	r2, r0, r1
35*3cab2bb3Spatrick	mls 	r0, r2, r1, r0
36*3cab2bb3Spatrick	bx      lr
37*3cab2bb3SpatrickLOCAL_LABEL(divzero):
38*3cab2bb3Spatrick	mov     r0, #0
39*3cab2bb3Spatrick	bx      lr
40*3cab2bb3Spatrick#else
41*3cab2bb3Spatrick    ESTABLISH_FRAME
42*3cab2bb3Spatrick    //  Set aside the sign of the dividend.
43*3cab2bb3Spatrick    mov     r4,     r0
44*3cab2bb3Spatrick    //  Take absolute value of a and b via abs(x) = (x^(x >> 31)) - (x >> 31).
45*3cab2bb3Spatrick    eor     r2,     r0, r0, asr #31
46*3cab2bb3Spatrick    eor     r3,     r1, r1, asr #31
47*3cab2bb3Spatrick    sub     r0,     r2, r0, asr #31
48*3cab2bb3Spatrick    sub     r1,     r3, r1, asr #31
49*3cab2bb3Spatrick    //  abs(a) % abs(b)
50*3cab2bb3Spatrick    bl     SYMBOL_NAME(__umodsi3)
51*3cab2bb3Spatrick    //  Apply sign of dividend to result and return.
52*3cab2bb3Spatrick    eor     r0,     r0, r4, asr #31
53*3cab2bb3Spatrick    sub     r0,     r0, r4, asr #31
54*3cab2bb3Spatrick    CLEAR_FRAME_AND_RETURN
55*3cab2bb3Spatrick#endif
56*3cab2bb3SpatrickEND_COMPILERRT_FUNCTION(__modsi3)
57*3cab2bb3Spatrick
58*3cab2bb3SpatrickNO_EXEC_STACK_DIRECTIVE
59*3cab2bb3Spatrick
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