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