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a809132921
Most MCUs apart from Cortex-M0 with Thumb 1 have an instruction for computing the "high part" of a multiplication (e.g., the upper 32 bits of a 32x32 multiply). When they do, gcc uses this to implement a small and fast overflow check using the __builtin_mul_overflow intrinsic, which is preferable to the guard division method previously used in smallint.c. However, in contrast to the previous mp_small_int_mul_overflow routine, which checks that the result fits not only within mp_int_t but is SMALL_INT_FITS(), __builtin_mul_overflow only checks for overflow of the C type. As a result, a slight change in the code flow is needed for MP_BINARY_OP_MULTIPLY. Other sites using mp_small_int_mul_overflow already had the result value flow through to a SMALL_INT_FITS check so they didn't need any additional changes. Do similarly for the _ll and _ull multiply overflows checks. Signed-off-by: Jeff Epler <jepler@gmail.com>
50 lines
1.8 KiB
C
50 lines
1.8 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2013, 2014 Damien P. George
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "py/smallint.h"
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mp_int_t mp_small_int_modulo(mp_int_t dividend, mp_int_t divisor) {
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// Python specs require that mod has same sign as second operand
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dividend %= divisor;
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if ((dividend < 0 && divisor > 0) || (dividend > 0 && divisor < 0)) {
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dividend += divisor;
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}
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return dividend;
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}
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mp_int_t mp_small_int_floor_divide(mp_int_t num, mp_int_t denom) {
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if (num >= 0) {
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if (denom < 0) {
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num += -denom - 1;
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}
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} else {
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if (denom >= 0) {
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num += -denom + 1;
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}
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}
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return num / denom;
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}
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