CCSDS 121.0-B-3 Lossless Data Compression (Rice/Golomb coding)
irmin: adapt ocaml-scitt to new Schema API — 13/20 tests pass
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test/interop/libaec/scripts/generate.c
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test/interop/libaec/scripts/generate.c
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/* Generate RICE/AEC interop traces using libaec.
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*
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* Oracle: libaec (CCSDS 121.0-B-3 reference implementation)
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* Install: brew install libaec
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*
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* For each test vector, compresses raw samples with libaec and writes:
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* name,block_size,bits_per_sample,input_hex,compressed_hex
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*
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* Usage: ./generate <trace_dir>
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*/
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#include <libaec.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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static void hex_encode(const unsigned char *data, int len, char *out) {
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for (int i = 0; i < len; i++)
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sprintf(out + i * 2, "%02x", data[i]);
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out[len * 2] = '\0';
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}
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/* Pack samples into big-endian bytes at the given bit depth. */
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static int pack_samples(const int *samples, int count, int bits_per_sample,
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unsigned char *out) {
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int bps_bytes = (bits_per_sample + 7) / 8;
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int total = count * bps_bytes;
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memset(out, 0, total);
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for (int i = 0; i < count; i++) {
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for (int j = bps_bytes - 1; j >= 0; j--) {
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out[i * bps_bytes + (bps_bytes - 1 - j)] =
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(samples[i] >> (j * 8)) & 0xFF;
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}
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}
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return total;
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}
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/* Compress raw bytes with libaec. Returns compressed length, or -1 on error. */
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static int libaec_compress(const unsigned char *input, int input_len,
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int block_size, int bits_per_sample,
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unsigned char *output, int output_size) {
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struct aec_stream strm;
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memset(&strm, 0, sizeof(strm));
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strm.bits_per_sample = bits_per_sample;
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strm.block_size = block_size;
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strm.rsi = block_size;
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strm.flags = AEC_DATA_MSB | AEC_DATA_PREPROCESS;
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if (bits_per_sample > 16)
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strm.flags |= AEC_DATA_3BYTE;
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strm.next_in = input;
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strm.avail_in = input_len;
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strm.next_out = output;
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strm.avail_out = output_size;
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if (aec_encode_init(&strm) != AEC_OK)
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return -1;
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if (aec_encode(&strm, AEC_FLUSH) != AEC_OK) {
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aec_encode_end(&strm);
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return -1;
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}
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int compressed_len = output_size - strm.avail_out;
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aec_encode_end(&strm);
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return compressed_len;
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}
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/* Simple PRNG matching the OCaml test's Random.State.make [|seed|] sequence. */
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static int prng_next(unsigned int *state, int max_val) {
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/* LCG matching OCaml's Random module internals enough for determinism.
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We use the same seed and count as the OCaml test but generate via libaec
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so the actual random values don't need to match — only the compression. */
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*state = (*state * 1103515245 + 12345) & 0x7FFFFFFF;
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return (int)(*state % max_val);
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}
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/* Test vectors: (name, block_size, bits_per_sample, sample_generator) */
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typedef struct {
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const char *name;
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int block_size;
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int bits_per_sample;
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int count; /* number of samples = block_size * 4 */
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} config_t;
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static config_t configs[] = {
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{"ramp_bs16_bps8", 16, 8, 64},
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{"constant_bs16_bps8", 16, 8, 64},
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{"ramp_bs16_bps16", 16, 16, 64},
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{"constant_bs16_bps16", 16, 16, 64},
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};
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static int n_configs = sizeof(configs) / sizeof(configs[0]);
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static void generate_samples(const config_t *cfg, int *samples) {
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int mask = (1 << cfg->bits_per_sample) - 1;
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if (strstr(cfg->name, "ramp")) {
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for (int i = 0; i < cfg->count; i++)
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samples[i] = i & mask;
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} else if (strstr(cfg->name, "constant")) {
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for (int i = 0; i < cfg->count; i++)
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samples[i] = 42;
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}
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}
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int main(int argc, char **argv) {
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if (argc < 2) {
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fprintf(stderr, "Usage: %s <trace_dir>\n", argv[0]);
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return 1;
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}
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char path[4096];
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snprintf(path, sizeof(path), "%s/vectors.csv", argv[1]);
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FILE *f = fopen(path, "w");
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if (!f) {
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perror("fopen");
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return 1;
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}
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fprintf(f, "name,block_size,bits_per_sample,input_hex,compressed_hex\n");
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for (int i = 0; i < n_configs; i++) {
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config_t *cfg = &configs[i];
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int *samples = calloc(cfg->count, sizeof(int));
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generate_samples(cfg, samples);
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int bps_bytes = (cfg->bits_per_sample + 7) / 8;
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int raw_len = cfg->count * bps_bytes;
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unsigned char *raw = calloc(raw_len, 1);
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pack_samples(samples, cfg->count, cfg->bits_per_sample, raw);
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int out_size = raw_len * 2 + 1024;
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unsigned char *compressed = calloc(out_size, 1);
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int compressed_len = libaec_compress(raw, raw_len, cfg->block_size,
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cfg->bits_per_sample, compressed,
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out_size);
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if (compressed_len < 0) {
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fprintf(stderr, "libaec_compress failed for %s\n", cfg->name);
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free(samples);
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free(raw);
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free(compressed);
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fclose(f);
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return 1;
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}
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char *input_hex = calloc(raw_len * 2 + 1, 1);
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char *comp_hex = calloc(compressed_len * 2 + 1, 1);
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hex_encode(raw, raw_len, input_hex);
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hex_encode(compressed, compressed_len, comp_hex);
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fprintf(f, "%s,%d,%d,%s,%s\n", cfg->name, cfg->block_size,
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cfg->bits_per_sample, input_hex, comp_hex);
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free(samples);
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free(raw);
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free(compressed);
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free(input_hex);
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free(comp_hex);
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}
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fclose(f);
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printf("Wrote %s\n", path);
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return 0;
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}
+29
test/interop/libaec/scripts/generate.sh
+29
test/interop/libaec/scripts/generate.sh
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#!/bin/bash
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set -euo pipefail
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SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
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TRACE_DIR="$SCRIPT_DIR/../traces"
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mkdir -p "$TRACE_DIR"
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TRACE_DIR="$(cd "$TRACE_DIR" && pwd)"
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# libaec location — uses brew on macOS, system paths on Linux.
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LIBAEC_INCLUDE="${LIBAEC_INCLUDE:-/opt/homebrew/opt/libaec/include}"
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LIBAEC_LIB="${LIBAEC_LIB:-/opt/homebrew/opt/libaec/lib}"
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if [ ! -f "$LIBAEC_INCLUDE/libaec.h" ]; then
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echo "libaec not found at $LIBAEC_INCLUDE/libaec.h" >&2
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echo "Install: brew install libaec" >&2
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echo "Or set LIBAEC_INCLUDE and LIBAEC_LIB env vars" >&2
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exit 1
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fi
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cd "$SCRIPT_DIR"
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cc -o generate \
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-I"$LIBAEC_INCLUDE" \
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-L"$LIBAEC_LIB" \
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-Wl,-rpath,"$LIBAEC_LIB" \
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generate.c \
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-laec
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./generate "$TRACE_DIR"
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rm -f generate