From 2e3aa7d8fd6ef4d7a64fd4db84629dba1e038d92 Mon Sep 17 00:00:00 2001
From: Christopher Kobayashi <software+android@disavowed.jp>
Date: Tue, 21 Apr 2020 18:11:21 +0900
Subject: [PATCH] Add makedc42 (convert raw image to DiskCopy 4.2)

---
 Makefile   |   6 +--
 makedc42.c | 130 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 133 insertions(+), 3 deletions(-)
 create mode 100644 makedc42.c

diff --git a/Makefile b/Makefile
index 0171061..5821bb0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,10 @@
-CFLAGS=	-O2 -Wall -Werror
+CFLAGS=	-O2 -Wall -Werror -ggdb
 
 
-all: dc42cksm
+all: dc42cksm makedc42
 
 install: all
 	install -m755 dc42cksm /usr/local/bin/
 
 clean:
-	rm -f dc42cksm *.o
+	rm -f dc42cksm makedc42 *.o
diff --git a/makedc42.c b/makedc42.c
new file mode 100644
index 0000000..000e91d
--- /dev/null
+++ b/makedc42.c
@@ -0,0 +1,130 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <arpa/inet.h>
+
+struct dc42_header {
+	u_int8_t	image_name_length;
+	char		image_name[63];
+	u_int32_t	data_size;
+	u_int32_t	tag_size;
+	u_int32_t	data_checksum;
+	u_int32_t	tag_checksum;
+	u_int8_t	encoding;
+	u_int8_t	format;
+	u_int16_t	magic_number;
+};
+
+enum encoding {
+	gcr_ssdd, /* 400k */
+	gcr_dsdd, /* 800k */
+	mfm_dsdd, /* 720k */
+	mfm_dshd  /* 1440k */
+};
+
+int main(int argc, char **argv)
+{
+	struct dc42_header header;
+
+	FILE *inputfile = NULL;
+	FILE *outputfile = NULL;
+	char outputfilename[255];
+	struct stat inputfile_stat;
+	u_int8_t *file_buffer = NULL;
+	u_int32_t rv = 0;
+	u_int16_t check;
+	int i;
+
+	if (argc != 2) {
+		printf("usage: makedc42 <inputfile>\n");
+		return -1;
+	}
+
+	memset(&header, 0x00, sizeof(header));
+
+	if ( (inputfile = fopen(argv[1], "r")) == NULL) {
+		printf("%s: does not exist.\n", argv[1]);
+		return -1;
+	}
+
+	if ( (stat(argv[1], &inputfile_stat)) ) {
+		printf("%s: could not stat\n", argv[1]);
+	}
+
+	printf("%s: size is %li\n", argv[1], inputfile_stat.st_size);
+
+	file_buffer = calloc(1, inputfile_stat.st_size);
+	if (file_buffer != NULL)
+		printf("%s: read %li bytes into buffer\n", argv[1],
+		    fread(file_buffer, 1, inputfile_stat.st_size, inputfile));
+
+	if (inputfile != NULL)
+		fclose(inputfile);
+
+	/* consistency checks */
+	check = (file_buffer[0] << 8) + file_buffer[1];
+	if (check != 0x4c4b) {
+		printf("%s: boot block failed consistency check (%x)\n", argv[1], check);
+		free(file_buffer);
+		return -1;
+	}
+	check = (file_buffer[0x400] << 8) + file_buffer[0x401];
+	if (check != 0x4244) {
+		printf("%s: VIB failed consistency check (%x)\n", argv[1], check);
+		free(file_buffer);
+		return -1;
+	}
+
+	header.magic_number = htons(0x0100);
+	header.image_name_length = strlen( (char *)&file_buffer[0x425]);
+	strncpy( (char *)&header.image_name, (char *)&file_buffer[0x425], 27);
+
+	printf("%s: embedded filename is \"%s\" (length %i)\n", argv[1], header.image_name, header.image_name_length);
+	snprintf(outputfilename, 255, "%s-dc42.img", header.image_name);
+	printf("%s: output filename is \"%s\"\n", argv[1], outputfilename);
+
+	switch (inputfile_stat.st_size) {
+		case 1474560:
+		  header.encoding = mfm_dshd;
+		  header.format = 0x22;
+		  break;
+		case 819200:
+		  header.encoding = gcr_dsdd;
+		  header.format = 0x22;
+		  break;
+		default:
+		  printf("%s: unknown size, not doing format/encoding\n", argv[1]);
+	}
+
+	header.data_size = htonl(inputfile_stat.st_size);
+
+	for (i = 0; i < inputfile_stat.st_size; i += 2) {
+		rv += (file_buffer[i] << 8) + file_buffer[i+1];
+    		rv = (rv >> 1) + (rv << 31);
+	}
+
+	printf("%s: calculated checksum %x\n", argv[1], rv);
+
+	header.data_checksum = htonl(rv);
+
+	outputfile = fopen(outputfilename, "w");
+
+	if (!outputfile) {
+		printf("%s: could not open output file\n", outputfilename);
+		free(file_buffer);
+		return -1;
+	}
+
+	fwrite(&header, sizeof(header), 1, outputfile);
+	fwrite(file_buffer, inputfile_stat.st_size, 1, outputfile);
+
+	if (file_buffer != NULL)
+		free(file_buffer);
+
+	if (outputfile != NULL)
+		fclose(outputfile);	
+
+	return 0;
+}