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/* minimal code example showing how to call the zfp (de)compressor */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "zfp.h"
/* compress or decompress array */
static int
compress(double* array, size_t nx, size_t ny, size_t nz, double tolerance, zfp_bool decompress)
{
int status = 0; /* return value: 0 = success */
zfp_type type; /* array scalar type */
zfp_field* field; /* array meta data */
zfp_stream* zfp; /* compressed stream */
void* buffer; /* storage for compressed stream */
size_t bufsize; /* byte size of compressed buffer */
bitstream* stream; /* bit stream to write to or read from */
size_t zfpsize; /* byte size of compressed stream */
/* allocate meta data for the 3D array a[nz][ny][nx] */
type = zfp_type_double;
field = zfp_field_3d(array, type, nx, ny, nz);
/* allocate meta data for a compressed stream */
zfp = zfp_stream_open(NULL);
/* set compression mode and parameters via one of four functions */
/* zfp_stream_set_reversible(zfp); */
/* zfp_stream_set_rate(zfp, rate, type, zfp_field_dimensionality(field), zfp_false); */
/* zfp_stream_set_precision(zfp, precision); */
zfp_stream_set_accuracy(zfp, tolerance);
/* allocate buffer for compressed data */
bufsize = zfp_stream_maximum_size(zfp, field);
buffer = malloc(bufsize);
/* associate bit stream with allocated buffer */
stream = stream_open(buffer, bufsize);
zfp_stream_set_bit_stream(zfp, stream);
zfp_stream_rewind(zfp);
/* compress or decompress entire array */
if (decompress) {
/* read compressed stream and decompress and output array */
zfpsize = fread(buffer, 1, bufsize, stdin);
if (!zfp_decompress(zfp, field)) {
fprintf(stderr, "decompression failed\n");
status = EXIT_FAILURE;
}
else
fwrite(array, sizeof(double), zfp_field_size(field, NULL), stdout);
}
else {
/* compress array and output compressed stream */
zfpsize = zfp_compress(zfp, field);
if (!zfpsize) {
fprintf(stderr, "compression failed\n");
status = EXIT_FAILURE;
}
else
fwrite(buffer, 1, zfpsize, stdout);
}
/* clean up */
zfp_field_free(field);
zfp_stream_close(zfp);
stream_close(stream);
free(buffer);
free(array);
return status;
}
int main(int argc, char* argv[])
{
/* use -d to decompress rather than compress data */
zfp_bool decompress = (argc == 2 && !strcmp(argv[1], "-d"));
/* allocate 100x100x100 array of doubles */
size_t nx = 100;
size_t ny = 100;
size_t nz = 100;
double* array = malloc(nx * ny * nz * sizeof(double));
if (!decompress) {
/* initialize array to be compressed */
size_t i, j, k;
for (k = 0; k < nz; k++)
for (j = 0; j < ny; j++)
for (i = 0; i < nx; i++) {
double x = 2.0 * i / nx;
double y = 2.0 * j / ny;
double z = 2.0 * k / nz;
array[i + nx * (j + ny * k)] = exp(-(x * x + y * y + z * z));
}
}
/* compress or decompress array */
return compress(array, nx, ny, nz, 1e-3, decompress);
}
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