xref: /freebsd/sys/libkern/arm/ldivmod.S (revision 3f0164abf32b9b761e0a2cb4bdca3a8b84f156d4)
1/*
2 * Copyright (C) 2012 Andrew Turner
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 */
27
28#include <machine/asm.h>
29__FBSDID("$FreeBSD$");
30
31#ifdef __ARM_EABI__
32
33/*
34 * These calculate:
35 * q = n / m
36 * With a remainer r.
37 *
38 * They take n in {r0, r1} and m in {r2, r3} then pass them into the
39 * helper function. The hepler functions return q in {r0, r1} as
40 * required by the API spec however r is returned on the stack. The
41 * ABI required us to return r in {r2, r3}.
42 *
43 * We need to allocate 8 bytes on the stack to store r, the link
44 * register, and a pointer to the space where the helper function
45 * will write r to. After returning from the helper fuinction we load
46 * the old link register and r from the stack and return.
47 */
48ENTRY_NP(__aeabi_ldivmod)
49	sub	sp, sp, #8	/* Space for the remainder */
50	stmfd	sp!, {sp, lr}	/* Save a pointer to the above space and lr */
51	bl	PIC_SYM(_C_LABEL(__kern_ldivmod), PLT)
52	ldr	lr, [sp, #4]	/* Restore lr */
53	add	sp, sp, #8	/* Move sp to the remainder value */
54	ldmfd	sp!, {r2, r3}	/* Load the remainder */
55	RET
56END(__aeabi_ldivmod)
57
58ENTRY_NP(__aeabi_uldivmod)
59	sub	sp, sp, #8	/* Space for the remainder */
60	stmfd	sp!, {sp, lr}	/* Save a pointer to the above space and lr */
61	bl	PIC_SYM(_C_LABEL(__qdivrem), PLT)
62	ldr	lr, [sp, #4]	/* Restore lr */
63	add	sp, sp, #8	/* Move sp to the remainder value */
64	ldmfd	sp!, {r2, r3}	/* Load the remainder */
65	RET
66END(__aeabi_uldivmod)
67
68#endif
69
70