]> git.ipfire.org Git - thirdparty/linux.git/blob - arch/c6x/lib/divremu.S
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156
[thirdparty/linux.git] / arch / c6x / lib / divremu.S
1 ;; SPDX-License-Identifier: GPL-2.0-or-later
2 ;; Copyright 2011 Free Software Foundation, Inc.
3 ;; Contributed by Bernd Schmidt <bernds@codesourcery.com>.
4 ;;
5
6 #include <linux/linkage.h>
7
8 .text
9 ENTRY(__c6xabi_divremu)
10 ;; We use a series of up to 31 subc instructions. First, we find
11 ;; out how many leading zero bits there are in the divisor. This
12 ;; gives us both a shift count for aligning (shifting) the divisor
13 ;; to the, and the number of times we have to execute subc.
14
15 ;; At the end, we have both the remainder and most of the quotient
16 ;; in A4. The top bit of the quotient is computed first and is
17 ;; placed in A2.
18
19 ;; Return immediately if the dividend is zero. Setting B4 to 1
20 ;; is a trick to allow us to leave the following insns in the jump
21 ;; delay slot without affecting the result.
22 mv .s2x A4, B1
23
24 [b1] lmbd .l2 1, B4, B1
25 ||[!b1] b .s2 B3 ; RETURN A
26 ||[!b1] mvk .d2 1, B4
27
28 ||[!b1] zero .s1 A5
29 mv .l1x B1, A6
30 || shl .s2 B4, B1, B4
31
32 ;; The loop performs a maximum of 28 steps, so we do the
33 ;; first 3 here.
34 cmpltu .l1x A4, B4, A2
35 [!A2] sub .l1x A4, B4, A4
36 || shru .s2 B4, 1, B4
37 || xor .s1 1, A2, A2
38
39 shl .s1 A2, 31, A2
40 || [b1] subc .l1x A4,B4,A4
41 || [b1] add .s2 -1, B1, B1
42 [b1] subc .l1x A4,B4,A4
43 || [b1] add .s2 -1, B1, B1
44
45 ;; RETURN A may happen here (note: must happen before the next branch)
46 __divremu0:
47 cmpgt .l2 B1, 7, B0
48 || [b1] subc .l1x A4,B4,A4
49 || [b1] add .s2 -1, B1, B1
50 [b1] subc .l1x A4,B4,A4
51 || [b1] add .s2 -1, B1, B1
52 || [b0] b .s1 __divremu0
53 [b1] subc .l1x A4,B4,A4
54 || [b1] add .s2 -1, B1, B1
55 [b1] subc .l1x A4,B4,A4
56 || [b1] add .s2 -1, B1, B1
57 [b1] subc .l1x A4,B4,A4
58 || [b1] add .s2 -1, B1, B1
59 [b1] subc .l1x A4,B4,A4
60 || [b1] add .s2 -1, B1, B1
61 [b1] subc .l1x A4,B4,A4
62 || [b1] add .s2 -1, B1, B1
63 ;; loop backwards branch happens here
64
65 ret .s2 B3
66 || mvk .s1 32, A1
67 sub .l1 A1, A6, A6
68 || extu .s1 A4, A6, A5
69 shl .s1 A4, A6, A4
70 shru .s1 A4, 1, A4
71 || sub .l1 A6, 1, A6
72 or .l1 A2, A4, A4
73 shru .s1 A4, A6, A4
74 nop
75 ENDPROC(__c6xabi_divremu)