furnace/extern/fftw/support/addchain.c

172 lines
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C
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/* addition-chain optimizer */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
static int verbose;
static int mulcost = 18;
static int ldcost = 2;
static int sqcost = 10;
static int reflcost = 8;
#define INFTY 100000
static int *answer;
static int best_so_far;
static void print_answer(int n, int t)
{
int i;
printf("| (%d, %d) -> [", n, t);
for (i = 0; i < t; ++i)
printf("%d;", answer[i]);
printf("] (* %d *)\n", best_so_far);
}
#define DO(i, j, k, cst) \
if (k < n) { \
int c = A[i] + A[j] + cst; \
if (c < A[k]) { \
A[k] = c; \
changed = 1; \
} \
}
#define DO3(i, j, l, k, cst) \
if (k < n) { \
int c = A[i] + A[j] + A[l] + cst; \
if (c < A[k]) { \
A[k] = c; \
changed = 1; \
} \
}
static int optimize(int n, int *A)
{
int i, j, k, changed, cst, cstmax;
do {
changed = 0;
for (i = 0; i < n; ++i) {
k = i + i;
DO(i, i, k, sqcost);
}
for (i = 0; i < n; ++i) {
for (j = 0; j <= i; ++j) {
k = i + j;
DO(i, j, k, mulcost);
k = i - j;
DO(i, j, k, mulcost);
k = i + j;
DO3(i, j, i - j, k, reflcost);
}
}
} while (changed);
cst = cstmax = 0;
for (i = 0; i < n; ++i) {
cst += A[i];
if (A[i] > cstmax) cstmax = A[i];
}
/* return cstmax; */
return cst;
}
static void search(int n, int t, int *A, int *B, int depth)
{
if (depth == 0) {
int i, tc;
for (i = 0; i < n; ++i)
A[i] = INFTY;
A[0] = 0; /* always free */
for (i = 1; i <= t; ++i)
A[B[-i]] = ldcost;
tc = optimize(n, A);
if (tc < best_so_far) {
best_so_far = tc;
for (i = 1; i <= t; ++i)
answer[t - i] = B[-i];
if (verbose)
print_answer(n, t);
}
} else {
for (B[0] = B[-1] + 1; B[0] < n; ++B[0])
search(n, t, A, B + 1, depth - 1);
}
}
static void doit(int n, int t)
{
int *A;
int *B;
A = malloc(n * sizeof(int));
B = malloc((t + 1) * sizeof(int));
answer = malloc(t * sizeof(int));
B[0] = 0;
best_so_far = INFTY;
search(n, t, A, B + 1, t);
print_answer(n, t);
free(A); free(B); free(answer);
}
int main(int argc, char *argv[])
{
int n = 32;
int t = 3;
int all;
int ch;
verbose = 0;
all = 0;
while ((ch = getopt(argc, argv, "n:t:m:l:r:s:va")) != -1) {
switch (ch) {
case 'n':
n = atoi(optarg);
break;
case 't':
t = atoi(optarg);
break;
case 'm':
mulcost = atoi(optarg);
break;
case 'l':
ldcost = atoi(optarg);
break;
case 's':
sqcost = atoi(optarg);
break;
case 'r':
reflcost = atoi(optarg);
break;
case 'v':
++verbose;
break;
case 'a':
++all;
break;
case '?':
fprintf(stderr, "use the source\n");
exit(1);
}
}
if (all) {
for (n = 4; n <= 64; n *= 2) {
int n1 = n - 1; if (n1 > 7) n1 = 7;
for (t = 1; t <= n1; ++t)
doit(n, t);
}
} else {
doit(n, t);
}
return 0;
}