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Assembler optimised 64 bit multiplication for coldfire: ~15% speedup. Proper max_iter decrease amount.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7278 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Jens Arnold 2005-08-01 20:49:41 +00:00
parent 96ea362a27
commit 0c29589d8a
1 changed files with 46 additions and 2 deletions
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48
apps/plugins/mandelbrot.c
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@ -129,6 +129,50 @@ asm (
"addc r2,r0 \n"
);
#define MUL64(a, b) mul64(a, b)
#elif defined CPU_COLDFIRE
long long mul64(long long f1, long long f2);
asm (
/* 64bit * 64bit -> 64bit multiplication. Works for both signed and unsigned */
".section .text,\"ax\",@progbits\n"
".global mul64 \n" /* Notation: abcd * efgh, where each letter */
".type mul64,@function\n" /* represents 16 bits. */
"mul64: \n"
"lea.l (-16,%sp),%sp \n"
"movem.l %d2-%d5,(%sp) \n"
"movem.l (20,%sp),%d0-%d3\n" /* %d0%d1 = abcd, %d2%d3 = efgh */
"mulu.l %d3,%d0 \n" /* %d0 = ab * gh */
"mulu.l %d1,%d2 \n" /* %d2 = cd * ef */
"add.l %d2,%d0 \n" /* %d0 += %d2 */
"move.l %d1,%d4 \n"
"swap %d4 \n" /* %d4 = dc */
"move.l %d3,%d5 \n"
"swap %d5 \n" /* %d5 = hg */
"move.l %d4,%d2 \n"
"mulu.w %d5,%d2 \n" /* %d2 = c * g */
"add.l %d2,%d0 \n" /* %d0 += %d2 */
"mulu.w %d3,%d4 \n" /* %d4 = c * h */
"mulu.w %d1,%d5 \n" /* %d5 = d * h */
"add.l %d4,%d5 \n" /* %d5 += %d4 */
"subx.l %d4,%d4 \n"
"neg.l %d4 \n" /* carry -> %d4 */
"swap %d4 \n"
"clr.w %d4 \n"
"swap %d5 \n"
"move.w %d5,%d4 \n"
"clr.w %d5 \n" /* %d4%d5 <<= 16 */
"mulu.w %d3,%d1 \n" /* %d1 = d * h */
"add.l %d5,%d1 \n"
"addx.l %d4,%d0 \n" /* %d0%d1 += %d4%d5 */
"movem.l (%sp),%d2-%d5 \n"
"lea.l (16,%sp),%sp\n"
"rts \n"
);
#define MUL64(a, b) mul64(a, b)
#else
#define MUL64(a, b) ((a)*(b))
#endif
@ -407,13 +451,13 @@ enum plugin_status plugin_start(struct plugin_api* api, void* parameter)
case MANDELBROT_MAXITER_DEC:
if (max_iter >= 15) {
max_iter -= max_iter >> 1;
max_iter -= max_iter / 3;
redraw = REDRAW_FULL;
}
break;
case MANDELBROT_MAXITER_INC:
max_iter += max_iter >> 1;
max_iter += max_iter / 2;
redraw = REDRAW_FULL;
break;