1/* SPDX-License-Identifier: GPL-2.0-or-later WITH GCC-exception-2.0 */
2#include <linux/linkage.h>
3#include <asm/asmmacro.h>
4#include <asm/core.h>
5
6ENTRY(__divsi3)
7
8	abi_entry_default
9#if XCHAL_HAVE_DIV32
10	quos	a2, a2, a3
11#else
12	xor	a7, a2, a3	/* sign = dividend ^ divisor */
13	do_abs	a6, a2, a4	/* udividend = abs (dividend) */
14	do_abs	a3, a3, a4	/* udivisor = abs (divisor) */
15	bltui	a3, 2, .Lle_one	/* check if udivisor <= 1 */
16	do_nsau	a5, a6, a2, a8	/* udividend_shift = nsau (udividend) */
17	do_nsau	a4, a3, a2, a8	/* udivisor_shift = nsau (udivisor) */
18	bgeu	a5, a4, .Lspecial
19
20	sub	a4, a4, a5	/* count = udivisor_shift - udividend_shift */
21	ssl	a4
22	sll	a3, a3		/* udivisor <<= count */
23	movi	a2, 0		/* quotient = 0 */
24
25	/* test-subtract-and-shift loop; one quotient bit on each iteration */
26#if XCHAL_HAVE_LOOPS
27	loopnez	a4, .Lloopend
28#endif /* XCHAL_HAVE_LOOPS */
29.Lloop:
30	bltu	a6, a3, .Lzerobit
31	sub	a6, a6, a3
32	addi	a2, a2, 1
33.Lzerobit:
34	slli	a2, a2, 1
35	srli	a3, a3, 1
36#if !XCHAL_HAVE_LOOPS
37	addi	a4, a4, -1
38	bnez	a4, .Lloop
39#endif /* !XCHAL_HAVE_LOOPS */
40.Lloopend:
41
42	bltu	a6, a3, .Lreturn
43	addi	a2, a2, 1	/* increment if udividend >= udivisor */
44.Lreturn:
45	neg	a5, a2
46	movltz	a2, a5, a7	/* return (sign < 0) ? -quotient : quotient */
47	abi_ret_default
48
49.Lle_one:
50	beqz	a3, .Lerror
51	neg	a2, a6		/* if udivisor == 1, then return... */
52	movgez	a2, a6, a7	/* (sign < 0) ? -udividend : udividend */
53	abi_ret_default
54
55.Lspecial:
56	bltu	a6, a3, .Lreturn0 /* if dividend < divisor, return 0 */
57	movi	a2, 1
58	movi	a4, -1
59	movltz	a2, a4, a7	/* else return (sign < 0) ? -1 : 1 */
60	abi_ret_default
61
62.Lerror:
63	/* Divide by zero: Use an illegal instruction to force an exception.
64	   The subsequent "DIV0" string can be recognized by the exception
65	   handler to identify the real cause of the exception.  */
66	ill
67	.ascii	"DIV0"
68
69.Lreturn0:
70	movi	a2, 0
71#endif /* XCHAL_HAVE_DIV32 */
72	abi_ret_default
73
74ENDPROC(__divsi3)
75EXPORT_SYMBOL(__divsi3)
76