--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/efrtest/dlcap-dec.c	Fri Dec 16 03:05:21 2022 +0000
@@ -0,0 +1,85 @@
+/*
+ * This program reads a TCH/EFS downlink capture produced with FreeCalypso tools
+ * (fw version with TCH downlink sniffing feature and fc-shell tch record)
+ * and feeds it to our libgsmefr decoder, making our best attempt to
+ * replicate the processing steps that must be performed by the original DSP.
+ *
+ * The output format is "robe" (raw big-endian).
+ */
+
+#include <ctype.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include "../libgsmefr/gsm_efr.h"
+
+main(argc, argv)
+	char **argv;
+{
+	FILE *inf, *outf;
+	struct EFR_decoder_state *state;
+	char linebuf[128];
+	int lineno, rc;
+	uint16_t status_words[3];
+	uint8_t tidsp_bytes[33], frame[EFR_RTP_FRAME_LEN];
+	int16_t params[EFR_NUM_PARAMS], pcm[160];
+	unsigned fn_mod_104;
+	int bfi, taf, sid;
+
+	if (argc != 3) {
+		fprintf(stderr, "usage: %s infile outfile\n", argv[0]);
+		exit(1);
+	}
+	inf = fopen(argv[1], "r");
+	if (!inf) {
+		perror(argv[1]);
+		exit(1);
+	}
+	outf = fopen(argv[2], "w");
+	if (!outf) {
+		perror(argv[2]);
+		exit(1);
+	}
+	state = EFR_decoder_create();
+	if (!state) {
+		perror("EFR_decoder_create()");
+		exit(1);
+	}
+	for (lineno = 1; fgets(linebuf, sizeof linebuf, inf); lineno++) {
+		/* support both old and new formats */
+		if (isxdigit(linebuf[0]) && isxdigit(linebuf[1]) &&
+		    isxdigit(linebuf[2]) && isxdigit(linebuf[3])) {
+			rc = parse_dlcap_common(linebuf, status_words,
+						tidsp_bytes);
+			if (rc < 0) {
+invalid:			fprintf(stderr,
+				"error: %s is not in the expected format\n",
+					argv[1]);
+				exit(1);
+			}
+			fn_mod_104 = 0;		/* won't have TAF */
+		} else if (!strncmp(linebuf, "EFR ", 4)) {
+			rc = parse_dlcap_common(linebuf + 4, status_words,
+						tidsp_bytes);
+			if (rc < 0)
+				goto invalid;
+			if (linebuf[85] != ' ')
+				goto invalid;
+			if (!isdigit(linebuf[86]))
+				goto invalid;
+			fn_mod_104 = strtoul(linebuf + 86, 0, 10);
+		} else
+			goto invalid;
+		/* processing, hoping to replicate what the DSP does */
+		efr_tidsp_to_std(tidsp_bytes, frame);
+		EFR_frame2params(frame, params);
+		bfi = (status_words[0] & 0x0204) != 0;
+		sid = (status_words[0] & 0x0018) >> 3;
+		taf = fn_mod_104 == 60;
+		EFR_decode_params(state, params, bfi, sid, taf, pcm);
+		write_pcm_to_robe(outf, pcm);
+	}
+	exit(0);
+}