Linux kernel mirror (for testing)
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linux
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)