116 lines
3.2 KiB
C
116 lines
3.2 KiB
C
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/* MN10300 64-bit division
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#ifndef _ASM_DIV64
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#define _ASM_DIV64
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#include <linux/types.h>
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extern void ____unhandled_size_in_do_div___(void);
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/*
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* Beginning with gcc 4.6, the MDR register is represented explicitly. We
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* must, therefore, at least explicitly clobber the register when we make
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* changes to it. The following assembly fragments *could* be rearranged in
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* order to leave the moves to/from the MDR register to the compiler, but the
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* gains would be minimal at best.
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*/
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#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
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# define CLOBBER_MDR_CC "mdr", "cc"
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#else
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# define CLOBBER_MDR_CC "cc"
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#endif
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/*
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* divide n by base, leaving the result in n and returning the remainder
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* - we can do this quite efficiently on the MN10300 by cascading the divides
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* through the MDR register
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*/
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#define do_div(n, base) \
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({ \
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unsigned __rem = 0; \
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if (sizeof(n) <= 4) { \
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asm("mov %1,mdr \n" \
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"divu %2,%0 \n" \
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"mov mdr,%1 \n" \
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: "+r"(n), "=d"(__rem) \
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: "r"(base), "1"(__rem) \
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: CLOBBER_MDR_CC \
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); \
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} else if (sizeof(n) <= 8) { \
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union { \
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unsigned long long l; \
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u32 w[2]; \
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} __quot; \
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__quot.l = n; \
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asm("mov %0,mdr \n" /* MDR = 0 */ \
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"divu %3,%1 \n" \
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/* __quot.MSL = __div.MSL / base, */ \
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/* MDR = MDR:__div.MSL % base */ \
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"divu %3,%2 \n" \
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/* __quot.LSL = MDR:__div.LSL / base, */ \
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/* MDR = MDR:__div.LSL % base */ \
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"mov mdr,%0 \n" \
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: "=d"(__rem), "=r"(__quot.w[1]), "=r"(__quot.w[0]) \
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: "r"(base), "0"(__rem), "1"(__quot.w[1]), \
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"2"(__quot.w[0]) \
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: CLOBBER_MDR_CC \
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); \
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n = __quot.l; \
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} else { \
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____unhandled_size_in_do_div___(); \
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} \
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__rem; \
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})
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/*
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* do an unsigned 32-bit multiply and divide with intermediate 64-bit product
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* so as not to lose accuracy
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* - we use the MDR register to hold the MSW of the product
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*/
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static inline __attribute__((const))
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unsigned __muldiv64u(unsigned val, unsigned mult, unsigned div)
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{
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unsigned result;
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asm("mulu %2,%0 \n" /* MDR:val = val*mult */
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"divu %3,%0 \n" /* val = MDR:val/div;
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* MDR = MDR:val%div */
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: "=r"(result)
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: "0"(val), "ir"(mult), "r"(div)
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: CLOBBER_MDR_CC
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);
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return result;
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}
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/*
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* do a signed 32-bit multiply and divide with intermediate 64-bit product so
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* as not to lose accuracy
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* - we use the MDR register to hold the MSW of the product
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*/
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static inline __attribute__((const))
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signed __muldiv64s(signed val, signed mult, signed div)
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{
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signed result;
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asm("mul %2,%0 \n" /* MDR:val = val*mult */
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"div %3,%0 \n" /* val = MDR:val/div;
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* MDR = MDR:val%div */
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: "=r"(result)
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: "0"(val), "ir"(mult), "r"(div)
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: CLOBBER_MDR_CC
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);
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return result;
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}
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#endif /* _ASM_DIV64 */
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