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Faster __mulsi routine

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From-SVN: r38736
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Nick Clifton 2001-01-06 00:46:33 +00:00 committed by Nick Clifton
parent f7114e1750
commit 0426e04997
2 changed files with 53 additions and 45 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
Fri Jan 5 16:34:18 2001 Nick Clifton <nickc@redhat.com>
* config/v850/lib1funcs.asm: Replace __mulsi3 routine with faster
version supplied by Matteo Frigo.
2001-01-05 Neil Booth <neil@daikokuya.demon.co.uk>
* cpp.texi: Update for -MQ.

93
gcc/config/v850/lib1funcs.asm
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@ -33,57 +33,60 @@ Boston, MA 02111-1307, USA. */
.type ___mulsi3,@function
/*
* In order to not deal with negative numbers (mulh is a signed multiply
* and we want an unsigned multiply, code the multiplication as a series
* of 7 bit multiplies).
* #define SHIFT 12
* #define MASK ((1 << SHIFT) - 1)
*
* #define STEP(i, j) \
* ({ \
* short a_part = (a >> (i)) & MASK; \
* short b_part = (b >> (j)) & MASK; \
* int res = (((int)a_part) * ((int)b_part)); \
* res; \
* })
*
* int __mulsi3 (unsigned a, unsigned b)
* int
* __mulsi3 (unsigned a, unsigned b)
* {
* int i, j;
* int ret = 0;
*
* for (i = 0; i < 32; i += 7)
* {
* short a_part = a & 0x7f;
* unsigned b_tmp = b;
* a >>= 7;
*
* for (j = 0; (i+j) < 32; j += 7)
* {
* short b_part = b_tmp & 0x7f;
* ret += (((int)a_part) * ((int)b_part)) << (i+j);
* b_tmp >>= 7;
* }
* }
*
* return ret;
* return STEP (0, 0) +
* ((STEP (SHIFT, 0) + STEP (0, SHIFT)) << SHIFT) +
* ((STEP (0, 2 * SHIFT) + STEP (SHIFT, SHIFT) + STEP (2 * SHIFT, 0))
* << (2 * SHIFT));
* }
*/
___mulsi3:
mov 0,r10 /* total */
mov 0,r14 /* i = 0, index for multiply a's part */
movea lo(31),r0,r16 /* upper bounds for loop */
.L5:
mov r7,r13 /* b_tmp = b */
andi 0x7f,r6,r15 /* a_part = (a & 127) */
shr 7,r6 /* a >>= 7 */
mov r14,r12 /* i+j = i */
.L9:
andi 0x7f,r13,r11 /* b_part = (b_tmp & 127) */
mulh r15,r11 /* ((int)a_part) * ((int)b_part) */
shr 7,r13 /* b_tmp >>= 7 */
shl r12,r11 /* (((int)a_part) * ((int)b_part)) << (i+j) */
add r11,r10 /* ret += (((int)a_part) * ((int)b_part)) << (i+j) */
add 7,r12 /* i+j += 7 */
cmp r16,r12 /* i+j < 32 */
ble .L9
add 7,r14 /* i += 7 */
cmp r16,r14 /* i < 32 */
ble .L5
jmp [r31] /* return */
mov r6,r13
movea lo(4095),r0,r16
and r16,r13
mov r7,r15
and r16,r15
mov r13,r10
mulh r15,r10
shr 12,r6
mov r6,r14
and r16,r14
mov r14,r11
mulh r15,r11
shr 12,r7
mov r7,r12
and r16,r12
shr 12,r7
and r16,r7
mulh r13,r7
shr 12,r6
mulh r12,r13
and r16,r6
add r13,r11
shl 12,r11
add r11,r10
mov r14,r11
mulh r12,r11
mulh r15,r6
add r11,r7
add r6,r7
shl 24,r7
add r7,r10
jmp [r31]
.size ___mulsi3,.-___mulsi3
#endif