1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
|
/* Copyright 2018 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* Cortex-M0 multiply-accumulate functions
*/
.syntax unified
.text
.thumb
@ uint64_t mula32(uint32_t a, uint32_t b, uint32_t c)
@
@ Multiply a (r0) and b (r1), add c (r2) and return the product in r1:r0
@
.thumb_func
.section .text.mula32
.global mula32
mula32:
push {r4, r5}
uxth r4, r0 /* r4 = a.lo16 */
uxth r5, r1 /* r5 = b.lo16 */
uxth r3, r2 /* r3 = c.lo16 */
muls r4, r5 /* r4 = a.lo16 * b.lo16 */
adds r4, r3 /* r4 = a.lo16 * b.lo16 + c.lo16 == r.lo32 */
lsrs r3, r0, 16 /* r3 = a.hi16 */
lsrs r2, r2, 16 /* r2 = c.hi16 */
muls r5, r3 /* r5 = a.hi16 * b.lo16 */
adds r5, r2 /* r5 = a.hi16 * b.lo16 + c.hi16 == r.mid32.1 */
uxth r2, r0 /* r2 = a.lo16 */
lsrs r1, r1, 16 /* r1 = b.hi16 */
muls r2, r1 /* r2 = a.lo16 * b.hi16 == r.mid32.2 */
muls r1, r3 /* r1 = b.hi16 * a.hi16 == r.hi32 */
movs r3, 0 /* r3 = 0 */
adds r5, r2 /* r5 = (r.mid32.1 + r.mid32.2).lo32 == r.mid.lo32 */
adcs r3, r3 /* r3 = (r.mid32.1 + r.mid32.2).hi32 == r.mid.hi32 */
lsls r0, r5, 16 /* r0 = r.mid.lo32.lo16 << 16 == r.mid.inpos.lo32 */
lsrs r5, r5, 16 /* r5 = r.mid.lo32.hi16 >> 16 */
lsls r3, r3, 16 /* r3 = r.mid.hi.lo16 << 16 */
adds r3, r5 /* r3 = r5 + r3 = r.mid.inpos.hi32 */
adds r0, r4 /* r0 = r.lo32 */
adcs r1, r3 /* r1 = r.hi32 */
pop {r4, r5}
bx lr
|
