diff options
Diffstat (limited to 'core/cortex-m0/mula.S')
| -rw-r--r-- | core/cortex-m0/mula.S | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/core/cortex-m0/mula.S b/core/cortex-m0/mula.S new file mode 100644 index 0000000000..fc0a6f3ee0 --- /dev/null +++ b/core/cortex-m0/mula.S @@ -0,0 +1,46 @@ +/* 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 + |