diff options
Diffstat (limited to 'lib/libutils/isoc/arch/arm/arm32_aeabi_ldivmod.c')
| -rw-r--r-- | lib/libutils/isoc/arch/arm/arm32_aeabi_ldivmod.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/lib/libutils/isoc/arch/arm/arm32_aeabi_ldivmod.c b/lib/libutils/isoc/arch/arm/arm32_aeabi_ldivmod.c new file mode 100644 index 0000000..f0074df --- /dev/null +++ b/lib/libutils/isoc/arch/arm/arm32_aeabi_ldivmod.c @@ -0,0 +1,126 @@ +/* + * Copyright (c) 2015, STMicroelectronics International N.V. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +/* struct lqr - stores qutient/remainder to handle divmod EABI interfaces. */ +struct lqr { + unsigned long long q; /* computed quotient */ + unsigned long long r; /* computed remainder */ + unsigned q_n; /* specficies if quotient shall be negative */ + unsigned r_n; /* specficies if remainder shall be negative */ +}; + +static void ul_div_qr(unsigned long long numerator, + unsigned long long denominator, struct lqr *qr); + + +static void division_lqr(unsigned long long n, unsigned long long p, + struct lqr *qr) +{ + unsigned long long i = 1, q = 0; + if (p == 0) { + qr->r = 0xFFFFFFFFFFFFFFFFULL; /* division by 0 */ + return; + } + + while ((p >> 63) == 0) { + i = i << 1; /* count the max division steps */ + p = p << 1; /* increase p until it has maximum size*/ + } + + while (i > 0) { + q = q << 1; /* write bit in q at index (size-1) */ + if (n >= p) { + n -= p; + q++; + } + p = p >> 1; /* decrease p */ + i = i >> 1; /* decrease remaining size in q */ + } + qr->r = n; + qr->q = q; +} + +static void ul_div_qr(unsigned long long numerator, + unsigned long long denominator, struct lqr *qr) +{ + + division_lqr(numerator, denominator, qr); + + /* negate quotient and/or remainder according to requester */ + if (qr->q_n) + qr->q = -qr->q; + if (qr->r_n) + qr->r = -qr->r; +} + +struct asm_ulqr { + unsigned long long v0; + unsigned long long v1; +}; + +/* called from assembly function __aeabi_uldivmod */ +void __ul_divmod(struct asm_ulqr *asm_ulqr); +void __ul_divmod(struct asm_ulqr *asm_ulqr) +{ + unsigned long long numerator = asm_ulqr->v0; + unsigned long long denominator = asm_ulqr->v1; + struct lqr qr = { .q_n = 0, .r_n = 0 }; + + ul_div_qr(numerator, denominator, &qr); + + asm_ulqr->v0 = qr.q; + asm_ulqr->v1 = qr.r; +} + +struct asm_lqr { + long long v0; + long long v1; +}; + +/* called from assembly function __aeabi_ldivmod */ +void __l_divmod(struct asm_lqr *asm_lqr); +void __l_divmod(struct asm_lqr *asm_lqr) +{ + long long numerator = asm_lqr->v0; + long long denominator = asm_lqr->v1; + struct lqr qr = { .q_n = 0, .r_n = 0 }; + + if (((numerator < 0) && (denominator > 0)) || + ((numerator > 0) && (denominator < 0))) + qr.q_n = 1; /* quotient shall be negate */ + if (numerator < 0) { + numerator = -numerator; + qr.r_n = 1; /* remainder shall be negate */ + } + if (denominator < 0) + denominator = -denominator; + + ul_div_qr(numerator, denominator, &qr); + + asm_lqr->v0 = qr.q; + asm_lqr->v1 = qr.r; +} |