diff options
Diffstat (limited to 'core/cortex-m0/mula.S')
| -rw-r--r-- | core/cortex-m0/mula.S | 37 |
1 files changed, 36 insertions, 1 deletions
diff --git a/core/cortex-m0/mula.S b/core/cortex-m0/mula.S index fc0a6f3ee0..02e617c328 100644 --- a/core/cortex-m0/mula.S +++ b/core/cortex-m0/mula.S @@ -2,7 +2,7 @@ * 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 + * Cortex-M0 multiply-accumulate[-accumulate] functions */ .syntax unified @@ -44,3 +44,38 @@ mula32: pop {r4, r5} bx lr +@ uint64_t mulaa32(uint32_t a, uint32_t b, uint32_t c, uint32_t d) +@ +@ Multiply a (r0) and b (r1), add c (r2), add d (r3) and return the product in +@ r1:r0 + .thumb_func + .section .text.mulaa32 + .global mulaa32 +mulaa32: + + push {r4, r5, r6} + uxth r5, r0 /* r5 = a.lo16 */ + uxth r6, r1 /* r6 = b.lo16 */ + uxth r4, r2 /* r4 = c.lo16 */ + muls r5, r6 /* r5 = a.lo16 * b.lo16 */ + adds r5, r4 /* r5 = a.lo16 * b.lo16 + c.lo16 == r.lo32 */ + lsrs r4, r0, 16 /* r4 = a.hi16 */ + lsrs r2, r2, 16 /* r2 = c.hi16 */ + muls r6, r4 /* r6 = a.hi16 * b.lo16 */ + adds r6, r2 /* r6 = 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, r4 /* r1 = b.hi16 * a.hi16 == r.hi32 */ + movs r4, 0 /* r4 = 0 */ + adds r6, r2 /* r6 = (r.mid32.1 + r.mid32.2).lo32 == r.mid.lo32 */ + adcs r4, r4 /* r4 = (r.mid32.1 + r.mid32.2).hi32 == r.mid.hi32 */ + lsls r0, r6, 16 /* r0 = r.mid.lo32.lo16 << 16 == r.mid.inpos.lo32 */ + lsrs r6, r6, 16 /* r6 = r.mid.lo32.hi16 >> 16 */ + lsls r4, r4, 16 /* r4 = r.mid.hi.lo16 << 16 */ + adds r0, r3 /* r0 = r.mid.inposition.lo32 + d */ + adcs r4, r6 /* r4 = r6 + r4 + carry = r.mid.inpos.hi32 */ + adds r0, r5 /* r0 = r.lo32 */ + adcs r1, r4 /* r1 = r.hi32 */ + pop {r4, r5, r6} + bx lr |