void mex(int nlhs, mxArray *plhs[],
int nrhs, mxArray const *prhs[])
{
if (nrhs != 4) mexErrMsgTxt("Needs 4 input arguments");
if (nlhs != 1) mexErrMsgTxt("Needs 1 output arguments");
mxArray *&aX = plhs[0]; // 1 x N output samples
mxArray const *aQ = prhs[0], // 1 x K input alias probabilities
*aJ = prhs[1], // 1 x K input alias table
*aR = prhs[2], // 1 x N input uniform sample 1
*aV = prhs[3]; // 1 x N input uniform sample 2
int K = mxGetN(aQ), // number of outcomes
N = mxGetN(aR); // number of samples
if(mxGetM(aQ) != 1)
mexErrMsgTxt("Dimensions of argument 1 invalid.");
if(mxGetM(aJ) != 1 || mxGetN(aJ) != K)
mexErrMsgTxt("Dimensions of arguments 1,2 inconsistent.");
if(mxGetM(aR) != 1)
mexErrMsgTxt("Dimensions of argument 3 invalid.");
if(mxGetM(aV) != 1 || mxGetN(aV) != N)
mexErrMsgTxt("Dimensions of arguments 3,4 inconsistent.");
if(mxGetClassID(aQ) != float_type<F>())
mexErrMsgTxt("Argument 1 has incorrect floating point class.");
if(mxGetClassID(aJ) != int_type<I>())
mexErrMsgTxt("Argument 2 has incorrect integer class.");
if(mxGetClassID(aR) != float_type<F>())
mexErrMsgTxt("Argument 3 has incorrect floating point class.");
if(mxGetClassID(aV) != float_type<F>())
mexErrMsgTxt("Argument 4 has incorrect floating point class.");
aX = mxCreateNumericMatrix(1, N, int_type<I>(), mxREAL);
I *X = (I*) mxGetPr(aX); // output samples
F *Q = (F*) mxGetPr(aQ); // input alias probabilities
I *J = (I*) mxGetPr(aJ); // input alias table
F *R = (F*) mxGetPr(aR); // input uniform sample 1
F *V = (F*) mxGetPr(aV); // input uniform sample 2
alias_draw(K, N, X, Q, J, R, V);
}
int main (int argc, char**argv) {
FILE *file;
FILE *tmp;
uint64_t j, i = 0;
uint32_t *res;
uint32_t *map;
uint32_t *cnt;
uint32_t draw;
double *table;
double c = 0;
/* getopt */
int opt;
int option_index = 0;
static const char *optstring = "1:2:c:N:a:f:m:i";
static const struct option long_options[] = {
{"alpha", required_argument, 0, 'a'},
{"elements", required_argument, 0, 'N'},
{"universe", required_argument, 0, 'm'},
{"count", required_argument, 0, 'c'},
{"file", required_argument, 0, 'f'},
{"seed1", required_argument, 0, '1'},
{"seed2", required_argument, 0, '2'},
{"info", required_argument, 0, 'i'},
};
double alpha = 0.5;
uint64_t count = (1 << 25);
uint32_t N = (1 << 20);
uint32_t m = UINT32_MAX;
char *filename = NULL;
while( (opt = getopt_long(argc, argv, optstring, long_options, &option_index)) != -1) {
switch(opt) {
case 'a':
alpha = strtod(optarg, NULL);
break;
case 'N':
N = strtol(optarg, NULL, 10);
break;
case 'm':
m = strtol(optarg, NULL, 10);
break;
case 'c':
count = strtoll(optarg, NULL, 10);
break;
case 'f':
filename = strndup(optarg, 256);
break;
case '1':
I1 = strtoll(optarg, NULL, 10);
break;
case '2':
I2 = strtoll(optarg, NULL, 10);
break;
case 'i':
default:
printusage(argv);
exit(EXIT_FAILURE);
}
if ( errno != 0 ) {
if (filename != NULL) {
free(filename);
}
xerror(strerror(errno), __LINE__, __FILE__);
}
}
if (filename == NULL) {
printusage(argv);
exit(EXIT_FAILURE);
}
cnt = xmalloc( sizeof(uint32_t) * N );
map = xmalloc( sizeof(uint32_t) * N );
table = xmalloc( sizeof(double) * N );
res = xmalloc( sizeof(uint32_t) * BUFFER );
tmp = tmpfile();
file = fopen(filename, "wb");
if ( file == NULL ) {
free(cnt);
free(res);
free(map);
free(filename);
free(table);
xerror("Failed to open/create file.", __LINE__, __FILE__);
}
fprintf(file, "#N: %"PRIu32"\n", N);
fprintf(file, "#Universe: %"PRIu32"\n", m);
fprintf(file, "#Alpha: %lf\n", alpha);
fprintf(file, "#Count: %"PRIu64"\n", count);
fprintf(file, "#Filename: %s\n", filename);
fprintf(file, "#Seed1: %"PRIu32"\n", I1);
fprintf(file, "#Seed2: %"PRIu32"\n", I2);
for (i = 1; i <= N; i++) {
table[i-1] = pow( (double)i, alpha );
c = c + (1. / table[i-1]);
}
c = 1./c;
for (i = 0; i < N; i++) {
cnt[i] = 0;
map[i] = i;
table[i] = (c / table[i]);
}
shuffle(map, N);
for (i = N; i < m; i++) {
j = xuni_rand()*(i+1);
if (j < N) {
map[j] = i;
}
}
alias_t *a = alias_preprocess(N, table);
free(table);
i = 0;
while ( likely(i < count) ) {
memset(res, '\0', sizeof(uint32_t)*BUFFER);
for (j = 0; likely( (i < count && j < BUFFER) ); j++, i++) {
draw = (uint32_t)alias_draw(a);
cnt[draw] += 1;
res[j] = map[draw];
}
if ( unlikely(fwrite(res, sizeof(uint32_t), j, tmp) < j) ) {
fclose(file);
fclose(tmp);
free(res);
free(filename);
free(map);
xerror("Failed to write all data.", __LINE__, __FILE__);
}
}
alias_free(a);
quicksort_map(cnt, 0, N-1, map);
// Print the weights of the top k probabilities into header of file
fprintf(file, "#====== TOP %d ======\n", TOPK);
for (i = 0; i < TOPK && i < N; i++) {
fprintf(file, "#%"PRIu32": %.10lf\n", map[i], (double)cnt[i]/count);
}
fprintf(file, "\n");
rewind(tmp);
memset(res, '\0', sizeof(uint32_t)*BUFFER);
uint32_t err;
while ( (err = fread(res, sizeof(uint32_t), BUFFER, tmp)) > 0 ) {
if ( unlikely(fwrite(res, sizeof(uint32_t), err, file) < err) ) {
fclose(file);
fclose(tmp);
free(res);
free(filename);
free(map);
xerror("Failed to write all data.", __LINE__, __FILE__);
}
}
fclose(file);
fclose(tmp);
free(res);
free(filename);
free(map);
return EXIT_SUCCESS;
}