1/* libgcc1 routines for 68000 w/o floating-point hardware.
2 Copyright (C) 1994, 1996, 1997, 1998 Free Software Foundation, Inc.
3
4This file is part of GNU CC.
5
6GNU CC is free software; you can redistribute it and/or modify it
7under the terms of the GNU General Public License as published by the
8Free Software Foundation; either version 2, or (at your option) any
9later version.
10
11In addition to the permissions in the GNU General Public License, the
12Free Software Foundation gives you unlimited permission to link the
13compiled version of this file with other programs, and to distribute
14those programs without any restriction coming from the use of this
15file. (The General Public License restrictions do apply in other
16respects; for example, they cover modification of the file, and
17distribution when not linked into another program.)
18
19This file is distributed in the hope that it will be useful, but
20WITHOUT ANY WARRANTY; without even the implied warranty of
21MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22General Public License for more details. */
23
24/* As a special exception, if you link this library with files
25 compiled with GCC to produce an executable, this does not cause
26 the resulting executable to be covered by the GNU General Public License.
27 This exception does not however invalidate any other reasons why
28 the executable file might be covered by the GNU General Public License. */
29
30/* Use this one for any 680x0; assumes no floating point hardware.
31 The trailing " '" appearing on some lines is for ANSI preprocessors. Yuk.
32 Some of this code comes from MINIX, via the folks at ericsson.
33 D. V. Henkel-Wallace (gumby@cygnus.com) Fete Bastille, 1992
34*/
35#include <linux/export.h>
36/* These are predefined by new versions of GNU cpp. */
37
38#ifndef __USER_LABEL_PREFIX__
39#define __USER_LABEL_PREFIX__ _
40#endif
41
42#ifndef __REGISTER_PREFIX__
43#define __REGISTER_PREFIX__
44#endif
45
46#ifndef __IMMEDIATE_PREFIX__
47#define __IMMEDIATE_PREFIX__ #
48#endif
49
50/* ANSI concatenation macros. */
51
52#define CONCAT1(a, b) CONCAT2(a, b)
53#define CONCAT2(a, b) a ## b
54
55/* Use the right prefix for global labels. */
56
57#define SYM(x) CONCAT1 (__USER_LABEL_PREFIX__, x)
58
59/* Use the right prefix for registers. */
60
61#define REG(x) CONCAT1 (__REGISTER_PREFIX__, x)
62
63/* Use the right prefix for immediate values. */
64
65#define IMM(x) CONCAT1 (__IMMEDIATE_PREFIX__, x)
66
67#define d0 REG (d0)
68#define d1 REG (d1)
69#define d2 REG (d2)
70#define d3 REG (d3)
71#define d4 REG (d4)
72#define d5 REG (d5)
73#define d6 REG (d6)
74#define d7 REG (d7)
75#define a0 REG (a0)
76#define a1 REG (a1)
77#define a2 REG (a2)
78#define a3 REG (a3)
79#define a4 REG (a4)
80#define a5 REG (a5)
81#define a6 REG (a6)
82#define fp REG (fp)
83#define sp REG (sp)
84
85 .text
86 .proc
87 .globl SYM (__udivsi3)
88SYM (__udivsi3):
89#if !(defined(__mcf5200__) || defined(__mcoldfire__))
90 movel d2, sp@-
91 movel sp@(12), d1 /* d1 = divisor */
92 movel sp@(8), d0 /* d0 = dividend */
93
94 cmpl IMM (0x10000), d1 /* divisor >= 2 ^ 16 ? */
95 jcc L3 /* then try next algorithm */
96 movel d0, d2
97 clrw d2
98 swap d2
99 divu d1, d2 /* high quotient in lower word */
100 movew d2, d0 /* save high quotient */
101 swap d0
102 movew sp@(10), d2 /* get low dividend + high rest */
103 divu d1, d2 /* low quotient */
104 movew d2, d0
105 jra L6
106
107L3: movel d1, d2 /* use d2 as divisor backup */
108L4: lsrl IMM (1), d1 /* shift divisor */
109 lsrl IMM (1), d0 /* shift dividend */
110 cmpl IMM (0x10000), d1 /* still divisor >= 2 ^ 16 ? */
111 jcc L4
112 divu d1, d0 /* now we have 16 bit divisor */
113 andl IMM (0xffff), d0 /* mask out divisor, ignore remainder */
114
115/* Multiply the 16 bit tentative quotient with the 32 bit divisor. Because of
116 the operand ranges, this might give a 33 bit product. If this product is
117 greater than the dividend, the tentative quotient was too large. */
118 movel d2, d1
119 mulu d0, d1 /* low part, 32 bits */
120 swap d2
121 mulu d0, d2 /* high part, at most 17 bits */
122 swap d2 /* align high part with low part */
123 tstw d2 /* high part 17 bits? */
124 jne L5 /* if 17 bits, quotient was too large */
125 addl d2, d1 /* add parts */
126 jcs L5 /* if sum is 33 bits, quotient was too large */
127 cmpl sp@(8), d1 /* compare the sum with the dividend */
128 jls L6 /* if sum > dividend, quotient was too large */
129L5: subql IMM (1), d0 /* adjust quotient */
130
131L6: movel sp@+, d2
132 rts
133
134#else /* __mcf5200__ || __mcoldfire__ */
135
136/* Coldfire implementation of non-restoring division algorithm from
137 Hennessy & Patterson, Appendix A. */
138 link a6,IMM (-12)
139 moveml d2-d4,sp@
140 movel a6@(8),d0
141 movel a6@(12),d1
142 clrl d2 | clear p
143 moveq IMM (31),d4
144L1: addl d0,d0 | shift reg pair (p,a) one bit left
145 addxl d2,d2
146 movl d2,d3 | subtract b from p, store in tmp.
147 subl d1,d3
148 jcs L2 | if no carry,
149 bset IMM (0),d0 | set the low order bit of a to 1,
150 movl d3,d2 | and store tmp in p.
151L2: subql IMM (1),d4
152 jcc L1
153 moveml sp@,d2-d4 | restore data registers
154 unlk a6 | and return
155 rts
156#endif /* __mcf5200__ || __mcoldfire__ */
157 EXPORT_SYMBOL(__udivsi3)
158

source code of linux/arch/m68k/lib/udivsi3.S