--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/trau-decode/extr-efr.c	Fri May 24 19:44:14 2024 +0000
@@ -0,0 +1,53 @@
+/*
+ * This module implements the EFR decoding part of trau-extr.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <gsm_efr.h>
+#include "osmo_bits.h"
+
+static void
+dbits_to_frame(d_bits, frame)
+	ubit_t *d_bits;
+	uint8_t *frame;
+{
+	ubit_t intermed[248], *ip;
+	uint8_t *op, mask;
+	unsigned nb;
+
+	intermed[0] = 1;
+	intermed[1] = 1;
+	intermed[2] = 0;
+	intermed[3] = 0;
+	bcopy(d_bits + 1, intermed + 4, 38);
+	bcopy(d_bits + 42, intermed + 42, 53);
+	bcopy(d_bits + 98, intermed + 95, 50);
+	bcopy(d_bits + 151, intermed + 145, 53);
+	bcopy(d_bits + 207, intermed + 198, 50);
+	ip = intermed;
+	op = frame;
+	for (nb = 0; nb < EFR_RTP_FRAME_LEN; nb++) {
+		*op = 0;
+		for (mask = 0x80; mask; mask >>= 1) {
+			if (*ip)
+				*op |= mask;
+			ip++;
+		}
+		op++;
+	}
+}
+
+void
+convert_efr_frame(d_bits, outf)
+	ubit_t *d_bits;
+	FILE *outf;
+{
+	uint8_t frame[EFR_RTP_FRAME_LEN];
+
+	dbits_to_frame(d_bits, frame);
+	fwrite(frame, 1, EFR_RTP_FRAME_LEN, outf);
+}