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◆ main openmsx / Contrib / dmk / svicpm2dmk.cc
5.0 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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#include "dmk-common.hh"
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#include <array>
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#include <cassert>
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#include <cstdint>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <span>
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#include <stdexcept>
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#include <string>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <vector>
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static constexpr unsigned TRACK_LENGTH = 6250;
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struct DiskInfo
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{
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	int gap1;
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	int gap2;
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	int gap3;
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	int gap4a;
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	int sectorsPerTrack;
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	int numberCylinders;
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	int sectorSizeCode;
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};
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static void fill(uint8_t*& p, int len, uint8_t value)
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{
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	memset(p, value, len);
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	p += len;
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}
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void convert(const DiskInfo& info, const std::string& input, const std::string& output)
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{
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	// Single or double sided input image?
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	struct stat st;
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	stat(input.c_str(), &st);
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	int numSides = [&]{
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		switch (st.st_size) {
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			case 174080:
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				return 1;
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			case 348160:
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				return 2;
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			default:
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				throw std::runtime_error(
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					"input filesize should be exactly 174080 or 348160 bytes.\n");
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		}
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	}();
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	int sectorSize = 128 << info.sectorSizeCode;
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	int totalTracks = numSides * info.numberCylinders;
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	int totalSectors = totalTracks * info.sectorsPerTrack;
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	int totalSize = totalSectors * sectorSize;
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	// sanity check
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	if (st.st_size != totalSize) {
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		throw std::runtime_error("Wrong input filesize");
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	}
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	File inf(input, "rb");
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	File outf(output, "wb");
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	int rawSectorLen =
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		12 + 10 + info.gap2 + 12 + 4 +
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		sectorSize + 2 + info.gap3;
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	int gap4b = TRACK_LENGTH - (info.gap4a + 12 + 4 + info.gap1 +
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		info.sectorsPerTrack * rawSectorLen);
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	assert(gap4b > 0);
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	int dmkTrackLen = TRACK_LENGTH + 128;
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	DmkHeader header;
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	memset(&header, 0, sizeof(header));
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	header.numTracks = info.numberCylinders;
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	header.trackLen[0] = dmkTrackLen & 0xff;
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	header.trackLen[1] = dmkTrackLen >> 8;
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	header.flags = ((numSides == 2) ? (0 << 4) : (1 << 4)) |
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	               (0 << 6); // double density (MFM)
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	outf.write(&header, sizeof(header));
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	std::vector<uint8_t*> addrPos(info.sectorsPerTrack);
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	std::vector<uint8_t*> dataPos(info.sectorsPerTrack);
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	std::vector<uint8_t> buf(dmkTrackLen); // zero-initialized
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	uint8_t* ip = buf.data() +   0; // pointer in IDAM table
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	uint8_t* tp = buf.data() + 128; // pointer in actual track data
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	fill(tp, info.gap4a, 0x4e); // gap4a
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	fill(tp,         12, 0x00); // sync
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	fill(tp,          3, 0xc2); // index mark
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	fill(tp,          1, 0xfc); //
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	fill(tp, info.gap1,  0x4e); // gap1
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	for (int sec = 0; sec < info.sectorsPerTrack; ++sec) {
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		fill(tp,         12, 0x00); // sync
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		fill(tp,          3, 0xa1); // ID addr mark
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		int pos = tp - buf.data();
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		assert(pos < 0x4000);
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		*ip++ = pos & 0xff;
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		*ip++ = (pos >> 8) | 0x80; // double density (MFM) sector
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		fill(tp,          1, 0xfe); // ID addr mark (cont)
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		addrPos[sec] = tp;
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		fill(tp,          6, 0x00); // C H R N CRC (overwritten later)
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		fill(tp, info.gap2,  0x4e); // gap2
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		fill(tp,         12, 0x00); // sync
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		fill(tp,          3, 0xa1); // data mark
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		fill(tp,          1, 0xfb); //
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		dataPos[sec] = tp;
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		fill(tp, sectorSize, 0x00); // sector data (overwritten later)
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		fill(tp,          2, 0x00); // CRC (overwritten later)
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		fill(tp, info.gap3,  0x4e); // gap3
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	}
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	fill(tp, gap4b, 0x4e); // gap4b
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	assert((tp - buf.data()) == dmkTrackLen);
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	for (int cyl = 0; cyl < info.numberCylinders; ++cyl) {
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		for (int head = 0; head < numSides; ++head) {
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			for (int sec = 0; sec < info.sectorsPerTrack; ++sec) {
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				uint8_t* ap = addrPos[sec];
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				*ap++ = cyl;
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				*ap++ = head;
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				*ap++ = sec + 1;
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				*ap++ = info.sectorSizeCode;
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				uint16_t addrCrc = 0xffff;
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				assert(ap >= &buf[8]);
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				const uint8_t* t1 = ap - 8;
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				for (int i = 0; i < 8; ++i) {
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					updateCrc(addrCrc, t1[i]);
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				}
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				*ap++ = addrCrc >> 8;
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				*ap++ = addrCrc & 0xff;
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				uint8_t* dp = dataPos[sec];
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				inf.read(dp, sectorSize);
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				dp += sectorSize;
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				uint16_t dataCrc = 0xffff;
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				const uint8_t* t2 = dp - sectorSize - 4;
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				for (int i = 0; i < sectorSize + 4; ++i) {
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					updateCrc(dataCrc, t2[i]);
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				}
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				*dp++ = dataCrc >> 8;
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				*dp++ = dataCrc & 0xff;
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			}
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			outf.write(buf.data(), dmkTrackLen);
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		}
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	}
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}
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int main(int argc, const char** argv)
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{
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	std::span arg(argv, argc);
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	if (arg.size() != 3) {
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		printf("svicpm2dmk\n"
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			"---------\n"
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			"\n"
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			"Utility to convert a SVI CP/M disk image into a DMK disk image.\n"
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			"\n"
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			"The SVI CP/M image is expected to have to following format:\n"
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			" - All tracks contain 17 sectors of 256 bytes.\n"
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			" - There are 40 tracks on the disk.\n"
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			" - The disk can be either single or double sided.\n"
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			"This means that the size of the input image should be exactly\n"
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			"174080 bytes for single sided disks or 348160 bytes for double\n"
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			"sided disks.\n"
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			"\n"
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			"Usage: %s <input.dsk> <output.dmk>\n", arg[0]);
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		exit(1);
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	}
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	// TODO add command line options to make these parameters configurable
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	DiskInfo info;
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	info.gap1  =  50;
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	info.gap2  =  22;
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	info.gap3  =  34;
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	info.gap4a =  80;
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	info.sectorsPerTrack = 17;
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	info.numberCylinders = 40;
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	info.sectorSizeCode = 1; // 256 = 128 << 1
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	try {
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		convert(info, arg[1], arg[2]);
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	} catch (std::exception& e) {
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		fprintf(stderr, "Error: %s\n", e.what());
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	}
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}