David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 1 | /* 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 | |
| 16 | extern void ____unhandled_size_in_do_div___(void); |
| 17 | |
| 18 | /* |
Richard Henderson | 5a4b65a | 2011-03-23 17:42:49 +0000 | [diff] [blame^] | 19 | * Beginning with gcc 4.6, the MDR register is represented explicitly. We |
| 20 | * must, therefore, at least explicitly clobber the register when we make |
| 21 | * changes to it. The following assembly fragments *could* be rearranged in |
| 22 | * order to leave the moves to/from the MDR register to the compiler, but the |
| 23 | * gains would be minimal at best. |
| 24 | */ |
| 25 | #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6) |
| 26 | # define CLOBBER_MDR_CC "mdr", "cc" |
| 27 | #else |
| 28 | # define CLOBBER_MDR_CC "cc" |
| 29 | #endif |
| 30 | |
| 31 | /* |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 32 | * divide n by base, leaving the result in n and returning the remainder |
| 33 | * - we can do this quite efficiently on the MN10300 by cascading the divides |
| 34 | * through the MDR register |
| 35 | */ |
| 36 | #define do_div(n, base) \ |
| 37 | ({ \ |
| 38 | unsigned __rem = 0; \ |
| 39 | if (sizeof(n) <= 4) { \ |
| 40 | asm("mov %1,mdr \n" \ |
| 41 | "divu %2,%0 \n" \ |
| 42 | "mov mdr,%1 \n" \ |
| 43 | : "+r"(n), "=d"(__rem) \ |
| 44 | : "r"(base), "1"(__rem) \ |
Richard Henderson | 5a4b65a | 2011-03-23 17:42:49 +0000 | [diff] [blame^] | 45 | : CLOBBER_MDR_CC \ |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 46 | ); \ |
| 47 | } else if (sizeof(n) <= 8) { \ |
| 48 | union { \ |
| 49 | unsigned long long l; \ |
| 50 | u32 w[2]; \ |
| 51 | } __quot; \ |
| 52 | __quot.l = n; \ |
| 53 | asm("mov %0,mdr \n" /* MDR = 0 */ \ |
| 54 | "divu %3,%1 \n" \ |
| 55 | /* __quot.MSL = __div.MSL / base, */ \ |
| 56 | /* MDR = MDR:__div.MSL % base */ \ |
| 57 | "divu %3,%2 \n" \ |
| 58 | /* __quot.LSL = MDR:__div.LSL / base, */ \ |
| 59 | /* MDR = MDR:__div.LSL % base */ \ |
| 60 | "mov mdr,%0 \n" \ |
| 61 | : "=d"(__rem), "=r"(__quot.w[1]), "=r"(__quot.w[0]) \ |
| 62 | : "r"(base), "0"(__rem), "1"(__quot.w[1]), \ |
| 63 | "2"(__quot.w[0]) \ |
Richard Henderson | 5a4b65a | 2011-03-23 17:42:49 +0000 | [diff] [blame^] | 64 | : CLOBBER_MDR_CC \ |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 65 | ); \ |
| 66 | n = __quot.l; \ |
| 67 | } else { \ |
| 68 | ____unhandled_size_in_do_div___(); \ |
| 69 | } \ |
| 70 | __rem; \ |
| 71 | }) |
| 72 | |
| 73 | /* |
| 74 | * do an unsigned 32-bit multiply and divide with intermediate 64-bit product |
| 75 | * so as not to lose accuracy |
| 76 | * - we use the MDR register to hold the MSW of the product |
| 77 | */ |
| 78 | static inline __attribute__((const)) |
| 79 | unsigned __muldiv64u(unsigned val, unsigned mult, unsigned div) |
| 80 | { |
| 81 | unsigned result; |
| 82 | |
| 83 | asm("mulu %2,%0 \n" /* MDR:val = val*mult */ |
| 84 | "divu %3,%0 \n" /* val = MDR:val/div; |
| 85 | * MDR = MDR:val%div */ |
| 86 | : "=r"(result) |
| 87 | : "0"(val), "ir"(mult), "r"(div) |
Richard Henderson | 5a4b65a | 2011-03-23 17:42:49 +0000 | [diff] [blame^] | 88 | : CLOBBER_MDR_CC |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 89 | ); |
| 90 | |
| 91 | return result; |
| 92 | } |
| 93 | |
| 94 | /* |
| 95 | * do a signed 32-bit multiply and divide with intermediate 64-bit product so |
| 96 | * as not to lose accuracy |
| 97 | * - we use the MDR register to hold the MSW of the product |
| 98 | */ |
| 99 | static inline __attribute__((const)) |
| 100 | signed __muldiv64s(signed val, signed mult, signed div) |
| 101 | { |
| 102 | signed result; |
| 103 | |
| 104 | asm("mul %2,%0 \n" /* MDR:val = val*mult */ |
| 105 | "div %3,%0 \n" /* val = MDR:val/div; |
| 106 | * MDR = MDR:val%div */ |
| 107 | : "=r"(result) |
| 108 | : "0"(val), "ir"(mult), "r"(div) |
Richard Henderson | 5a4b65a | 2011-03-23 17:42:49 +0000 | [diff] [blame^] | 109 | : CLOBBER_MDR_CC |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 110 | ); |
| 111 | |
| 112 | return result; |
| 113 | } |
| 114 | |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 115 | #endif /* _ASM_DIV64 */ |