circuitpython/py/smallint.c

80 lines
2.7 KiB
C

/*
* This file is part of the Micro Python project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2013, 2014 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "mpconfig.h"
#include "misc.h"
#include "qstr.h"
#include "obj.h"
#include "smallint.h"
bool mp_small_int_mul_overflow(mp_int_t x, mp_int_t y) {
// Check for multiply overflow; see CERT INT32-C
if (x > 0) { // x is positive
if (y > 0) { // x and y are positive
if (x > (MP_SMALL_INT_MAX / y)) {
return true;
}
} else { // x positive, y nonpositive
if (y < (MP_SMALL_INT_MIN / x)) {
return true;
}
} // x positive, y nonpositive
} else { // x is nonpositive
if (y > 0) { // x is nonpositive, y is positive
if (x < (MP_SMALL_INT_MIN / y)) {
return true;
}
} else { // x and y are nonpositive
if (x != 0 && y < (MP_SMALL_INT_MAX / x)) {
return true;
}
} // End if x and y are nonpositive
} // End if x is nonpositive
return false;
}
mp_int_t mp_small_int_modulo(mp_int_t dividend, mp_int_t divisor) {
mp_int_t lsign = (dividend >= 0) ? 1 :-1;
mp_int_t rsign = (divisor >= 0) ? 1 :-1;
dividend %= divisor;
if (lsign != rsign) {
dividend += divisor;
}
return dividend;
}
mp_int_t mp_small_int_floor_divide(mp_int_t num, mp_int_t denom) {
mp_int_t lsign = num > 0 ? 1 : -1;
mp_int_t rsign = denom > 0 ? 1 : -1;
if (lsign == -1) {num *= -1;}
if (rsign == -1) {denom *= -1;}
if (lsign != rsign){
return - ( num + denom - 1) / denom;
} else {
return num / denom;
}
}