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David Howellsb920de12008-02-08 04:19:31 -08001/* MN10300 64-bit division
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11#ifndef _ASM_DIV64
12#define _ASM_DIV64
13
14#include <linux/types.h>
15
16extern void ____unhandled_size_in_do_div___(void);
17
18/*
19 * divide n by base, leaving the result in n and returning the remainder
20 * - we can do this quite efficiently on the MN10300 by cascading the divides
21 * through the MDR register
22 */
23#define do_div(n, base) \
24({ \
25 unsigned __rem = 0; \
26 if (sizeof(n) <= 4) { \
27 asm("mov %1,mdr \n" \
28 "divu %2,%0 \n" \
29 "mov mdr,%1 \n" \
30 : "+r"(n), "=d"(__rem) \
31 : "r"(base), "1"(__rem) \
32 : "cc" \
33 ); \
34 } else if (sizeof(n) <= 8) { \
35 union { \
36 unsigned long long l; \
37 u32 w[2]; \
38 } __quot; \
39 __quot.l = n; \
40 asm("mov %0,mdr \n" /* MDR = 0 */ \
41 "divu %3,%1 \n" \
42 /* __quot.MSL = __div.MSL / base, */ \
43 /* MDR = MDR:__div.MSL % base */ \
44 "divu %3,%2 \n" \
45 /* __quot.LSL = MDR:__div.LSL / base, */ \
46 /* MDR = MDR:__div.LSL % base */ \
47 "mov mdr,%0 \n" \
48 : "=d"(__rem), "=r"(__quot.w[1]), "=r"(__quot.w[0]) \
49 : "r"(base), "0"(__rem), "1"(__quot.w[1]), \
50 "2"(__quot.w[0]) \
51 : "cc" \
52 ); \
53 n = __quot.l; \
54 } else { \
55 ____unhandled_size_in_do_div___(); \
56 } \
57 __rem; \
58})
59
60/*
61 * do an unsigned 32-bit multiply and divide with intermediate 64-bit product
62 * so as not to lose accuracy
63 * - we use the MDR register to hold the MSW of the product
64 */
65static inline __attribute__((const))
66unsigned __muldiv64u(unsigned val, unsigned mult, unsigned div)
67{
68 unsigned result;
69
70 asm("mulu %2,%0 \n" /* MDR:val = val*mult */
71 "divu %3,%0 \n" /* val = MDR:val/div;
72 * MDR = MDR:val%div */
73 : "=r"(result)
74 : "0"(val), "ir"(mult), "r"(div)
75 );
76
77 return result;
78}
79
80/*
81 * do a signed 32-bit multiply and divide with intermediate 64-bit product so
82 * as not to lose accuracy
83 * - we use the MDR register to hold the MSW of the product
84 */
85static inline __attribute__((const))
86signed __muldiv64s(signed val, signed mult, signed div)
87{
88 signed result;
89
90 asm("mul %2,%0 \n" /* MDR:val = val*mult */
91 "div %3,%0 \n" /* val = MDR:val/div;
92 * MDR = MDR:val%div */
93 : "=r"(result)
94 : "0"(val), "ir"(mult), "r"(div)
95 );
96
97 return result;
98}
99
100extern __attribute__((const))
101uint64_t div64_64(uint64_t dividend, uint64_t divisor);
102
103#endif /* _ASM_DIV64 */