mirror of
https://github.com/Telecominfraproject/OpenCellular.git
synced 2025-12-31 02:51:26 +00:00
3227f921e7
We put each assembly function in its own section. So the sections for
64-bit signed and unsigned divide end up too far apart for b<cond>
(8-bit delta) or b (11-bit delta). Instead, use bl, which has no such
limit. This is a little less efficient in the case where numerator
and denominator are both positive, but equivalent if either or both is
negative, and is far outweighed by the cost of the unsigned divide
itself.
The other alternative would be to put both uldivmod and ldivmod in the
same section. However, we're often tight on code size on cortex-M0
parts, so that's less desirable.
BUG=chrome-os-partner:26126
BRANCH=minnie
TEST=add the following function
static int command_divtest(int argc, char **argv)
{
int64_t a, b, c;
char *e;
if (argc < 2)
return EC_ERROR_PARAM_COUNT;
a = strtoi(argv[1], &e, 0);
b = strtoi(argv[2], &e, 0);
c = a / b;
ccprintf("%d / %d = %d\n", (int)a, (int)b, (int)c);
return EC_SUCCESS;
}
DECLARE_CONSOLE_COMMAND(dt, command_divtest,
"a b",
"Divide test",
NULL);
and test with divides in all 4 quadrants (+/- 20 divided by +/- 5,
for example)
Change-Id: I2a5e49c4534044c2f509e325f8dd6bdf10b544c4
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/252243
Reviewed-by: Alec Berg <alecaberg@chromium.org>
93 lines
2.0 KiB
ArmAsm
93 lines
2.0 KiB
ArmAsm
/* Runtime ABI for the ARM Cortex-M0
|
|
* ldivmod.S: signed 64 bit division (quotient and remainder)
|
|
*
|
|
* Copyright (c) 2012 Jörg Mische <bobbl@gmx.de>
|
|
*
|
|
* Permission to use, copy, modify, and/or distribute this software for any
|
|
* purpose with or without fee is hereby granted, provided that the above
|
|
* copyright notice and this permission notice appear in all copies.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
|
|
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
|
|
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
|
|
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
|
|
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
|
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
|
|
* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
|
*/
|
|
|
|
|
|
|
|
.syntax unified
|
|
.text
|
|
.thumb
|
|
.cpu cortex-m0
|
|
|
|
|
|
|
|
@ {long long quotient, long long remainder}
|
|
@ __aeabi_ldivmod(long long numerator, long long denominator)
|
|
@
|
|
@ Divide r1:r0 by r3:r2 and return the quotient in r1:r0 and the remainder in
|
|
@ r3:r2 (all signed)
|
|
@
|
|
.thumb_func
|
|
.section .text.__aeabi_ldivmod
|
|
.global __aeabi_ldivmod
|
|
__aeabi_ldivmod:
|
|
|
|
cmp r1, #0
|
|
bge L_num_pos
|
|
|
|
push {r4, lr}
|
|
movs r4, #0 @ num = -num
|
|
rsbs r0, r0, #0
|
|
sbcs r4, r1
|
|
mov r1, r4
|
|
|
|
cmp r3, #0
|
|
bge L_neg_both
|
|
|
|
movs r4, #0 @ den = -den
|
|
rsbs r2, r2, #0
|
|
sbcs r4, r3
|
|
mov r3, r4
|
|
bl __aeabi_uldivmod
|
|
movs r4, #0 @ rem = -rem
|
|
rsbs r2, r2, #0
|
|
sbcs r4, r3
|
|
mov r3, r4
|
|
pop {r4, pc}
|
|
|
|
L_neg_both:
|
|
bl __aeabi_uldivmod
|
|
movs r4, #0 @ quot = -quot
|
|
rsbs r0, r0, #0
|
|
sbcs r4, r1
|
|
mov r1, r4
|
|
movs r4, #0 @ rem = -rem
|
|
rsbs r2, r2, #0
|
|
sbcs r4, r3
|
|
mov r3, r4
|
|
pop {r4, pc}
|
|
|
|
L_num_pos:
|
|
cmp r3, #0
|
|
blt L_den_neg
|
|
push {r4, lr}
|
|
bl __aeabi_uldivmod @ offset too big for b / bge
|
|
pop {r4, pc}
|
|
|
|
L_den_neg:
|
|
push {r4, lr}
|
|
movs r4, #0 @ den = -den
|
|
rsbs r2, r2, #0
|
|
sbcs r4, r3
|
|
mov r3, r4
|
|
bl __aeabi_uldivmod
|
|
movs r4, #0 @ quot = -quot
|
|
rsbs r0, r0, #0
|
|
sbcs r4, r1
|
|
mov r1, r4
|
|
pop {r4, pc}
|