--- a/miscutil/amr2efr.c	Sun Nov 27 05:43:26 2022 +0000
+++ b/miscutil/amr2efr.c	Sun Nov 27 05:59:10 2022 +0000
@@ -18,27 +18,37 @@
 main(argc, argv)
 	char **argv;
 {
+	char *infname, *outfname;
 	FILE *inf, *outf;
-	int hdrb;
+	int wrong_flag, hdrb;
 	uint8_t frm_in[31], frm_out[31];
 	unsigned bit_a, bit_n;
 
-	if (argc != 3) {
-		fprintf(stderr, "usage: %s input.amr output.gsmx\n", argv[0]);
+	if (argc == 3 && argv[1][0] != '-') {
+		wrong_flag = 0;
+		infname = argv[1];
+		outfname = argv[2];
+	} else if (argc == 4 && !strcmp(argv[1], "-w")) {
+		wrong_flag = 1;
+		infname = argv[2];
+		outfname = argv[3];
+	} else {
+		fprintf(stderr, "usage: %s [-w] input.amr output.gsmx\n",
+			argv[0]);
 		exit(1);
 	}
-	inf = fopen(argv[1], "r");
+	inf = fopen(infname, "r");
 	if (!inf) {
-		perror(argv[1]);
+		perror(infname);
 		exit(1);
 	}
 	if (fread(frm_in, 1, 6, inf) != 6 || bcmp(frm_in, amr_file_hdr, 6)) {
-		fprintf(stderr, "error: %s is not in AMR format\n", argv[1]);
+		fprintf(stderr, "error: %s is not in AMR format\n", infname);
 		exit(1);
 	}
-	outf = fopen(argv[2], "w");
+	outf = fopen(outfname, "w");
 	if (!outf) {
-		perror(argv[2]);
+		perror(outfname);
 		exit(1);
 	}
 	for (;;) {
@@ -47,17 +57,20 @@
 			break;
 		if ((hdrb & 0x78) != 0x38) {
 			fprintf(stderr, "error: unexpected content in %s\n",
-				argv[1]);
+				infname);
 			exit(1);
 		}
 		if (fread(frm_in, 1, 31, inf) != 31) {
-			fprintf(stderr, "error: short read from %s\n", argv[1]);
+			fprintf(stderr, "error: short read from %s\n", infname);
 			exit(1);
 		}
 		bzero(frm_out, 31);
 		frm_out[0] = 0xC0;
 		for (bit_a = 0; bit_a < 244; bit_a++) {
-			bit_n = amr_122_bit_order[bit_a];
+			if (wrong_flag)
+				bit_n = bit_a;
+			else
+				bit_n = amr_122_bit_order[bit_a];
 			msb_set_bit(frm_out, 4 + bit_n,
 				    msb_get_bit(frm_in, bit_a));
 		}