1/* SPDX-License-Identifier: GPL-2.0 */
2#include <linux/linkage.h>
3
4/*
5* Divide operation for 32 bit integers.
6*	Input :	Dividend in Reg r5
7*		Divisor in Reg r6
8*	Output: Result in Reg r3
9*/
10	.text
11	.globl	__divsi3
12	.type __divsi3, @function
13	.ent __divsi3
14__divsi3:
15	.frame	r1, 0, r15
16
17	addik	r1, r1, -16
18	swi	r28, r1, 0
19	swi	r29, r1, 4
20	swi	r30, r1, 8
21	swi	r31, r1, 12
22
23	beqi	r6, div_by_zero /* div_by_zero - division error */
24	beqi	r5, result_is_zero /* result is zero */
25	bgeid	r5, r5_pos
26	xor	r28, r5, r6 /* get the sign of the result */
27	rsubi	r5, r5, 0 /* make r5 positive */
28r5_pos:
29	bgei	r6, r6_pos
30	rsubi	r6, r6, 0 /* make r6 positive */
31r6_pos:
32	addik	r30, r0, 0 /* clear mod */
33	addik	r3, r0, 0 /* clear div */
34	addik	r29, r0, 32 /* initialize the loop count */
35
36	/* first part try to find the first '1' in the r5 */
37div0:
38	blti	r5, div2 /* this traps r5 == 0x80000000 */
39div1:
40	add	r5, r5, r5 /* left shift logical r5 */
41	bgtid	r5, div1
42	addik	r29, r29, -1
43div2:
44	/* left shift logical r5 get the '1' into the carry */
45	add	r5, r5, r5
46	addc	r30, r30, r30 /* move that bit into the mod register */
47	rsub	r31, r6, r30 /* try to subtract (r30 a r6) */
48	blti	r31, mod_too_small
49	/* move the r31 to mod since the result was positive */
50	or	r30, r0, r31
51	addik	r3, r3, 1
52mod_too_small:
53	addik	r29, r29, -1
54	beqi	r29, loop_end
55	add	r3, r3, r3 /* shift in the '1' into div */
56	bri	div2 /* div2 */
57loop_end:
58	bgei	r28, return_here
59	brid	return_here
60	rsubi	r3, r3, 0 /* negate the result */
61div_by_zero:
62result_is_zero:
63	or	r3, r0, r0 /* set result to 0 */
64return_here:
65/* restore values of csrs and that of r3 and the divisor and the dividend */
66	lwi	r28, r1, 0
67	lwi	r29, r1, 4
68	lwi	r30, r1, 8
69	lwi	r31, r1, 12
70	rtsd	r15, 8
71	addik	r1, r1, 16
72
73.size __divsi3, . - __divsi3
74.end __divsi3
75