/* Signed and unsigned multiplication and division and modulus for CRIS. | |

Contributed by Axis Communications. | |

Written by Hans-Peter Nilsson <hp@axis.se>, c:a 1992. | |

Copyright (C) 1998-2021 Free Software Foundation, Inc. | |

This file is part of GCC. | |

GCC is free software; you can redistribute it and/or modify it | |

under the terms of the GNU General Public License as published by the | |

Free Software Foundation; either version 3, or (at your option) any | |

later version. | |

This file is distributed in the hope that it will be useful, but | |

WITHOUT ANY WARRANTY; without even the implied warranty of | |

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |

General Public License for more details. | |

Under Section 7 of GPL version 3, you are granted additional | |

permissions described in the GCC Runtime Library Exception, version | |

3.1, as published by the Free Software Foundation. | |

You should have received a copy of the GNU General Public License and | |

a copy of the GCC Runtime Library Exception along with this program; | |

see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |

<http://www.gnu.org/licenses/>. */ | |

/* Note that we provide prototypes for all "const" functions, to attach | |

the const attribute. This is necessary in 2.7.2 - adding the | |

attribute to the function *definition* is a syntax error. | |

This did not work with e.g. 2.1; back then, the return type had to | |

be "const". */ | |

#include "config.h" | |

#if defined (__CRIS_arch_version) && __CRIS_arch_version >= 3 | |

#define LZ(v) __builtin_clz (v) | |

#endif | |

/* In (at least) the 4.7 series, GCC doesn't automatically choose the | |

most optimal strategy, possibly related to insufficient modelling of | |

delay-slot costs. */ | |

#if defined (__CRIS_arch_version) && __CRIS_arch_version >= 10 | |

#define SIGNMULT(s, a) ((s) * (a)) /* Cheap multiplication, better than branch. */ | |

#else | |

#define SIGNMULT(s, a) ((s) < 0 ? -(a) : (a)) /* Branches are still better. */ | |

#endif | |

#if defined (L_udivsi3) || defined (L_divsi3) || defined (L_umodsi3) \ | |

|| defined (L_modsi3) | |

/* Result type of divmod worker function. */ | |

struct quot_rem | |

{ | |

long quot; | |

long rem; | |

}; | |

/* This is the worker function for div and mod. It is inlined into the | |

respective library function. Parameter A must have bit 31 == 0. */ | |

static __inline__ struct quot_rem | |

do_31div (unsigned long a, unsigned long b) | |

__attribute__ ((__const__, __always_inline__)); | |

static __inline__ struct quot_rem | |

do_31div (unsigned long a, unsigned long b) | |

{ | |

/* Adjust operands and result if a is 31 bits. */ | |

long extra = 0; | |

int quot_digits = 0; | |

if (b == 0) | |

{ | |

struct quot_rem ret; | |

ret.quot = 0xffffffff; | |

ret.rem = 0xffffffff; | |

return ret; | |

} | |

if (a < b) | |

return (struct quot_rem) { 0, a }; | |

#ifdef LZ | |

if (b <= a) | |

{ | |

quot_digits = LZ (b) - LZ (a); | |

quot_digits += (a >= (b << quot_digits)); | |

b <<= quot_digits; | |

} | |

#else | |

while (b <= a) | |

{ | |

b <<= 1; | |

quot_digits++; | |

} | |

#endif | |

/* Is a 31 bits? Note that bit 31 is handled by the caller. */ | |

if (a & 0x40000000) | |

{ | |

/* Then make b:s highest bit max 0x40000000, because it must have | |

been 0x80000000 to be 1 bit higher than a. */ | |

b >>= 1; | |

/* Adjust a to be maximum 0x3fffffff, i.e. two upper bits zero. */ | |

if (a >= b) | |

{ | |

a -= b; | |

extra = 1 << (quot_digits - 1); | |

} | |

else | |

{ | |

a -= b >> 1; | |

/* Remember that we adjusted a by subtracting b * 2 ** Something. */ | |

extra = 1 << quot_digits; | |

} | |

/* The number of quotient digits will be one less, because | |

we just adjusted b. */ | |

quot_digits--; | |

} | |

/* Now do the division part. */ | |

/* Subtract b and add ones to the right when a >= b | |

i.e. "a - (b - 1) == (a - b) + 1". */ | |

b--; | |

#define DS __asm__ ("dstep %2,%0" : "=r" (a) : "0" (a), "r" (b)); \ | |

__attribute__ ((__fallthrough__)) | |

switch (quot_digits) | |

{ | |

case 32: DS; case 31: DS; case 30: DS; case 29: DS; | |

case 28: DS; case 27: DS; case 26: DS; case 25: DS; | |

case 24: DS; case 23: DS; case 22: DS; case 21: DS; | |

case 20: DS; case 19: DS; case 18: DS; case 17: DS; | |

case 16: DS; case 15: DS; case 14: DS; case 13: DS; | |

case 12: DS; case 11: DS; case 10: DS; case 9: DS; | |

case 8: DS; case 7: DS; case 6: DS; case 5: DS; | |

case 4: DS; case 3: DS; case 2: DS; case 1: DS; | |

case 0:; | |

} | |

{ | |

struct quot_rem ret; | |

ret.quot = (a & ((1 << quot_digits) - 1)) + extra; | |

ret.rem = a >> quot_digits; | |

return ret; | |

} | |

} | |

#ifdef L_udivsi3 | |

unsigned long | |

__Udiv (unsigned long a, unsigned long b) __attribute__ ((__const__)); | |

unsigned long | |

__Udiv (unsigned long a, unsigned long b) | |

{ | |

long extra = 0; | |

/* Adjust operands and result, if a and/or b is 32 bits. */ | |

/* Effectively: b & 0x80000000. */ | |

if ((long) b < 0) | |

return a >= b; | |

/* Effectively: a & 0x80000000. */ | |

if ((long) a < 0) | |

{ | |

int tmp = 0; | |

if (b == 0) | |

return 0xffffffff; | |

#ifdef LZ | |

tmp = LZ (b); | |

#else | |

for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--) | |

; | |

tmp = 31 - tmp; | |

#endif | |

if ((b << tmp) > a) | |

{ | |

extra = 1 << (tmp-1); | |

a -= b << (tmp - 1); | |

} | |

else | |

{ | |

extra = 1 << tmp; | |

a -= b << tmp; | |

} | |

} | |

return do_31div (a, b).quot+extra; | |

} | |

#endif /* L_udivsi3 */ | |

#ifdef L_divsi3 | |

long | |

__Div (long a, long b) __attribute__ ((__const__)); | |

long | |

__Div (long a, long b) | |

{ | |

long extra = 0; | |

long sign = (b < 0) ? -1 : 1; | |

long res; | |

/* We need to handle a == -2147483648 as expected and must while | |

doing that avoid producing a sequence like "abs (a) < 0" as GCC | |

may optimize out the test. That sequence may not be obvious as | |

we call inline functions. Testing for a being negative and | |

handling (presumably much rarer than positive) enables us to get | |

a bit of optimization for an (accumulated) reduction of the | |

penalty of the 0x80000000 special-case. */ | |

if (a < 0) | |

{ | |

sign = -sign; | |

if ((a & 0x7fffffff) == 0) | |

{ | |

/* We're at 0x80000000. Tread carefully. */ | |

a -= SIGNMULT (sign, b); | |

extra = sign; | |

} | |

a = -a; | |

} | |

res = do_31div (a, __builtin_labs (b)).quot; | |

return SIGNMULT (sign, res) + extra; | |

} | |

#endif /* L_divsi3 */ | |

#ifdef L_umodsi3 | |

unsigned long | |

__Umod (unsigned long a, unsigned long b) __attribute__ ((__const__)); | |

unsigned long | |

__Umod (unsigned long a, unsigned long b) | |

{ | |

/* Adjust operands and result if a and/or b is 32 bits. */ | |

if ((long) b < 0) | |

return a >= b ? a - b : a; | |

if ((long) a < 0) | |

{ | |

int tmp = 0; | |

if (b == 0) | |

return a; | |

#ifdef LZ | |

tmp = LZ (b); | |

#else | |

for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--) | |

; | |

tmp = 31 - tmp; | |

#endif | |

if ((b << tmp) > a) | |

{ | |

a -= b << (tmp - 1); | |

} | |

else | |

{ | |

a -= b << tmp; | |

} | |

} | |

return do_31div (a, b).rem; | |

} | |

#endif /* L_umodsi3 */ | |

#ifdef L_modsi3 | |

long | |

__Mod (long a, long b) __attribute__ ((__const__)); | |

long | |

__Mod (long a, long b) | |

{ | |

long sign = 1; | |

long res; | |

/* We need to handle a == -2147483648 as expected and must while | |

doing that avoid producing a sequence like "abs (a) < 0" as GCC | |

may optimize out the test. That sequence may not be obvious as | |

we call inline functions. Testing for a being negative and | |

handling (presumably much rarer than positive) enables us to get | |

a bit of optimization for an (accumulated) reduction of the | |

penalty of the 0x80000000 special-case. */ | |

if (a < 0) | |

{ | |

sign = -1; | |

if ((a & 0x7fffffff) == 0) | |

/* We're at 0x80000000. Tread carefully. */ | |

a += __builtin_labs (b); | |

a = -a; | |

} | |

res = do_31div (a, __builtin_labs (b)).rem; | |

return SIGNMULT (sign, res); | |

} | |

#endif /* L_modsi3 */ | |

#endif /* L_udivsi3 || L_divsi3 || L_umodsi3 || L_modsi3 */ | |

/* | |

* Local variables: | |

* eval: (c-set-style "gnu") | |

* indent-tabs-mode: t | |

* End: | |

*/ |