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156 lines
4.2 KiB
156 lines
4.2 KiB
/*
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* Copyright (c) 2017-2019, Arm Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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/*
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* Form ABI specifications:
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* int __aeabi_idiv(int numerator, int denominator);
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* unsigned __aeabi_uidiv(unsigned numerator, unsigned denominator);
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*
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* typedef struct { int quot; int rem; } idiv_return;
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* typedef struct { unsigned quot; unsigned rem; } uidiv_return;
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*
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* __value_in_regs idiv_return __aeabi_idivmod(int numerator,
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* int *denominator);
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* __value_in_regs uidiv_return __aeabi_uidivmod(unsigned *numerator,
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* unsigned denominator);
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*/
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/* struct qr - stores quotient/remainder to handle divmod EABI interfaces. */
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struct qr {
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unsigned int q; /* computed quotient */
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unsigned int r; /* computed remainder */
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unsigned int q_n; /* specifies if quotient shall be negative */
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unsigned int r_n; /* specifies if remainder shall be negative */
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};
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static void uint_div_qr(unsigned int numerator, unsigned int denominator,
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struct qr *qr);
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/* returns in R0 and R1 by tail calling an asm function */
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unsigned int __aeabi_uidivmod(unsigned int numerator, unsigned int denominator);
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unsigned int __aeabi_uidiv(unsigned int numerator, unsigned int denominator);
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/* returns in R0 and R1 by tail calling an asm function */
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signed int __aeabi_idivmod(signed int numerator, signed int denominator);
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signed int __aeabi_idiv(signed int numerator, signed int denominator);
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/*
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* __ste_idivmod_ret_t __aeabi_idivmod(signed numerator, signed denominator)
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* Numerator and Denominator are received in R0 and R1.
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* Where __ste_idivmod_ret_t is returned in R0 and R1.
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*
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* __ste_uidivmod_ret_t __aeabi_uidivmod(unsigned numerator,
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* unsigned denominator)
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* Numerator and Denominator are received in R0 and R1.
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* Where __ste_uidivmod_ret_t is returned in R0 and R1.
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*/
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#ifdef __GNUC__
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signed int ret_idivmod_values(signed int quotient, signed int remainder);
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unsigned int ret_uidivmod_values(unsigned int quotient, unsigned int remainder);
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#else
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#error "Compiler not supported"
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#endif
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static void division_qr(unsigned int n, unsigned int p, struct qr *qr)
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{
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unsigned int i = 1, q = 0;
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if (p == 0) {
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qr->r = 0xFFFFFFFF; /* division by 0 */
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return;
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}
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while ((p >> 31) == 0) {
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i = i << 1; /* count the max division steps */
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p = p << 1; /* increase p until it has maximum size*/
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}
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while (i > 0) {
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q = q << 1; /* write bit in q at index (size-1) */
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if (n >= p) {
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n -= p;
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q++;
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}
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p = p >> 1; /* decrease p */
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i = i >> 1; /* decrease remaining size in q */
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}
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qr->r = n;
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qr->q = q;
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}
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static void uint_div_qr(unsigned int numerator, unsigned int denominator,
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struct qr *qr)
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{
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division_qr(numerator, denominator, qr);
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/* negate quotient and/or remainder according to requester */
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if (qr->q_n)
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qr->q = -qr->q;
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if (qr->r_n)
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qr->r = -qr->r;
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}
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unsigned int __aeabi_uidiv(unsigned int numerator, unsigned int denominator)
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{
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struct qr qr = { .q_n = 0, .r_n = 0 };
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uint_div_qr(numerator, denominator, &qr);
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return qr.q;
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}
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unsigned int __aeabi_uidivmod(unsigned int numerator, unsigned int denominator)
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{
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struct qr qr = { .q_n = 0, .r_n = 0 };
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uint_div_qr(numerator, denominator, &qr);
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return ret_uidivmod_values(qr.q, qr.r);
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}
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signed int __aeabi_idiv(signed int numerator, signed int denominator)
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{
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struct qr qr = { .q_n = 0, .r_n = 0 };
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if (((numerator < 0) && (denominator > 0)) ||
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((numerator > 0) && (denominator < 0)))
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qr.q_n = 1; /* quotient shall be negate */
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if (numerator < 0) {
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numerator = -numerator;
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qr.r_n = 1; /* remainder shall be negate */
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}
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if (denominator < 0)
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denominator = -denominator;
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uint_div_qr(numerator, denominator, &qr);
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return qr.q;
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}
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signed int __aeabi_idivmod(signed int numerator, signed int denominator)
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{
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struct qr qr = { .q_n = 0, .r_n = 0 };
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if (((numerator < 0) && (denominator > 0)) ||
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((numerator > 0) && (denominator < 0)))
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qr.q_n = 1; /* quotient shall be negate */
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if (numerator < 0) {
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numerator = -numerator;
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qr.r_n = 1; /* remainder shall be negate */
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}
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if (denominator < 0)
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denominator = -denominator;
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uint_div_qr(numerator, denominator, &qr);
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return ret_idivmod_values(qr.q, qr.r);
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}
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