442 lines
15 KiB
C
Executable File
442 lines
15 KiB
C
Executable File
#include <assert.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <string.h>
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// Forward declarations; see definitions for documentation.
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static uint32_t crc32(const uint8_t *buf, size_t size);
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static void serialise_track(uint8_t *dest, const uint8_t *src, uint8_t track_number, bool is_prodos);
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int main(int argc, char *argv[]) {
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// Announce failure if there are anything other than three arguments.
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if(argc != 3) {
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printf("USAGE: dsk2woz input.dsk output.woz\n");
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return -1;
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}
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// Attempt to read the standard DSK number of bytes into a buffer.
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FILE *const dsk_file = fopen(argv[1], "rb");
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if(!dsk_file) {
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printf("ERROR: could not open %s for reading\n", argv[1]);
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return -2;
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}
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const size_t dsk_image_size = 35 * 16 * 256;
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uint8_t dsk[dsk_image_size];
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const size_t bytes_read = fread(dsk, 1, dsk_image_size, dsk_file);
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fclose(dsk_file);
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// Determine from the filename whether to use Pro-DOS sector order.
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bool has_p = false;
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bool has_dot = false;
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const char *extension = argv[1] + strlen(argv[1]);
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do {
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has_p = *extension == 'p';
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has_dot = *extension == '.';
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--extension;
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} while(extension > argv[1] && *extension != '/' && *extension != '.');
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const bool is_prodos = has_p && has_dot;
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// If the DSK image was too short, announce failure. Some DSK files
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// seem empirically to be too long, but it's unclear that the extra
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// bytes actually mean anything — they're usually not many.
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if(bytes_read != dsk_image_size) {
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printf("ERROR: DSK image too small\n");
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return -3;
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}
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// Create a buffer for the portion of the WOZ image that comes after
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// the 12-byte header. The header will house the CRC, which will be
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// calculated later.
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const size_t woz_image_size = 256 - 12 + 35*6656;
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uint8_t woz[woz_image_size];
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memset(woz, 0, sizeof(woz));
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#define set_int32(location, value) \
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woz[location] = (value) & 0xff; \
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woz[location+1] = ((value) >> 8) & 0xff; \
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woz[location+2] = ((value) >> 16) & 0xff; \
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woz[location+3] = (value) >> 24;
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/*
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WOZ image item 1: an INFO chunk.
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*/
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strcpy((char *)&woz[0], "INFO"); // Chunk ID.
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set_int32(4, 60); // Chunk size.
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woz[8] = 1; // INFO version: 1.
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woz[9] = 1; // Disk type: 5.25".
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woz[10] = 0; // Write protection: disabled.
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woz[11] = 0; // Cross-track synchronised image: no.
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woz[12] = 1; // MC3470 fake bits have been removed: yes.
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// (or, rather, were never inserted)
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// Append creator, which needs to be padded out to 32
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// bytes with space characters.
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const char creator[] = "dsk2woz 1.0";
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const size_t creator_length = strlen(creator);
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assert(creator_length < 32);
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strcpy((char *)&woz[13], creator);
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memset(&woz[13 + strlen(creator)], 32 - strlen(creator), ' ');
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// Chunk should be padded with 0s to reach 60 bytes in length;
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// the buffer was memset to 0 at initialisation so that's implicit.
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/*
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WOZ image item 2: a TMAP chunk.
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*/
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strcpy((char *)&woz[68], "TMAP"); // Chunk ID.
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set_int32(72, 160); // Chunk size.
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// This is a DSK conversion, so the TMAP table simply maps every
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// track that exists to:
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// (i) its integral position;
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// (ii) the quarter-track position before its integral position; and
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// (iii) the quarter-track position after its integral position.
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//
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// The remaining quarter-track position maps to nothing, which in
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// WOZ is indicated with a value of 255.
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// Let's start by filling the entire TMAP with empty tracks.
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memset(&woz[76], 0xff, 160);
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// Then we will add in the mappings.
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for(size_t c = 0; c < 35; ++c) {
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const size_t track_position = 76 + (c << 2);
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if(c > 0) woz[track_position - 1] = c;
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woz[track_position] = woz[track_position + 1] = c;
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}
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/*
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WOZ image item 3: a TRKS chunk.
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*/
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strcpy((char *)&woz[236], "TRKS"); // Chunk ID.
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set_int32(240, 35*6656); // Chunk size.
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// The output pointer holds a byte position into the WOZ buffer.
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size_t output_pointer = 244;
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// Write out all 35 tracks.
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for(size_t c = 0; c < 35; ++c) {
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serialise_track(&woz[output_pointer], &dsk[c * 16 * 256], c, is_prodos);
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output_pointer += 6656;
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}
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#undef set_int32
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/*
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WOZ image output.
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*/
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FILE *const woz_file = fopen(argv[2], "wb");
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if(!woz_file) {
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printf("ERROR: Could not open %s for writing\n", argv[2]);
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return -5;
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}
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fputs("WOZ1", woz_file);
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fputc(0xff, woz_file);
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fputs("\n\r\n", woz_file);
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const uint32_t crc = crc32(woz, sizeof(woz));
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fputc(crc & 0xff, woz_file);
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fputc((crc >> 8) & 0xff, woz_file);
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fputc((crc >> 16) & 0xff, woz_file);
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fputc(crc >> 24, woz_file);
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const size_t length_written = fwrite(woz, 1, sizeof(woz), woz_file);
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fclose(woz_file);
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if(length_written != sizeof(woz)) {
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printf("ERROR: Could not write full WOZ image\n");
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return -6;
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}
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return 0;
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}
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/*
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CRC generator. Essentially that of Gary S. Brown from 1986, but I've
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fixed the initial value. This is exactly the code advocated by the
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WOZ file specifications (with some extra consts).
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*/
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static const uint32_t crc32_tab[] = {
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0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
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0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
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0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
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0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
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0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
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0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
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0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
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0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
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0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
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0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
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0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
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0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
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0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
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0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
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0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
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0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
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0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
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0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
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0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
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0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
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0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
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0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
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0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
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0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
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0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
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0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
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0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
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0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
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0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
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0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
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0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
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0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
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0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
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0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
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0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
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0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
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0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
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0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
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0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
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0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
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0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
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0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
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0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
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};
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/*!
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Computes the CRC32 of an input buffer.
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@param buf A pointer to the data to compute a CRC32 from.
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@param size The size of the data to compute a CRC32 from.
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@return The computed CRC32.
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*/
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static uint32_t crc32(const uint8_t *buf, size_t size) {
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uint32_t crc = ~0;
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size_t byte = 0;
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while (size--) {
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crc = crc32_tab[(crc ^ buf[byte]) & 0xFF] ^ (crc >> 8);
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++byte;
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}
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return ~crc;
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}
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/*
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DSK sector serialiser. Constructs the 6-and-2 DOS 3.3-style on-disk
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representation of a DOS logical-order sector dump.
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*/
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/*!
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Appends a bit to a buffer at a supplied position, returning the
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position immediately after the bit. The first bit added to a buffer
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will be stored in the MSB of the first byte. The second will be stored in
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bit 6. The eighth will be stored in the MSB of the second byte. Etc.
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@param buffer The buffer to write into.
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@param position The position to write at.
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@param value An indicator of the bit to write. If this is zero then a 0 is written; otherwise a 1 is written.
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@return The position immediately after the bit.
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*/
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static size_t write_bit(uint8_t *buffer, size_t position, int value) {
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buffer[position >> 3] |= (value ? 0x80 : 0x00) >> (position & 7);
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return position + 1;
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}
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/*!
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Appends a byte to a buffer at a supplied position, returning the
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position immediately after the byte. This is equivalent to calling
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write_bit eight times, supplying bit 7, then bit 6, down to bit 0.
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@param buffer The buffer to write into.
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@param position The position to write at.
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@param value The byte to write.
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@return The position immediately after the byte.
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*/
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static size_t write_byte(uint8_t *buffer, size_t position, int value) {
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const size_t shift = position & 7;
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const size_t byte_position = position >> 3;
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buffer[byte_position] |= value >> shift;
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if(shift) buffer[byte_position+1] |= value << (8 - shift);
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return position + 8;
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}
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/*!
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Encodes a byte into Apple 4-and-4 format and appends it to a buffer.
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@param buffer The buffer to write into.
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@param position The position to write at.
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@param value The byte to encode and write.
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@return The position immediately after the encoded byte.
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*/
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static size_t write_4_and_4(uint8_t *buffer, size_t position, int value) {
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position = write_byte(buffer, position, (value >> 1) | 0xaa);
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position = write_byte(buffer, position, value | 0xaa);
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return position;
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}
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/*!
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Appends a 6-and-2-style sync word to a buffer.
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@param buffer The buffer to write into.
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@param position The position to write at.
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@return The position immediately after the sync word.
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*/
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static size_t write_sync(uint8_t *buffer, size_t position) {
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position = write_byte(buffer, position, 0xff);
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return position + 2; // Skip two bits, i.e. leave them as 0s.
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}
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/*!
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Converts a 256-byte source buffer into the 343 byte values that
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contain the Apple 6-and-2 encoding of that buffer.
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@param dest The at-least-343 byte buffer to which the encoded sector is written.
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@param src The 256-byte source data.
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*/
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static void encode_6_and_2(uint8_t *dest, const uint8_t *src) {
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const uint8_t six_and_two_mapping[] = {
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0x96, 0x97, 0x9a, 0x9b, 0x9d, 0x9e, 0x9f, 0xa6,
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0xa7, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb2, 0xb3,
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0xb4, 0xb5, 0xb6, 0xb7, 0xb9, 0xba, 0xbb, 0xbc,
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0xbd, 0xbe, 0xbf, 0xcb, 0xcd, 0xce, 0xcf, 0xd3,
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0xd6, 0xd7, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde,
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0xdf, 0xe5, 0xe6, 0xe7, 0xe9, 0xea, 0xeb, 0xec,
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0xed, 0xee, 0xef, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6,
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0xf7, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
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};
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// Fill in byte values: the first 86 bytes contain shuffled
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// and combined copies of the bottom two bits of the sector
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// contents; the 256 bytes afterwards are the remaining
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// six bits.
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const uint8_t bit_reverse[] = {0, 2, 1, 3};
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for(size_t c = 0; c < 84; ++c) {
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dest[c] =
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bit_reverse[src[c]&3] |
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(bit_reverse[src[c + 86]&3] << 2) |
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(bit_reverse[src[c + 172]&3] << 4);
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}
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dest[84] =
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(bit_reverse[src[84]&3] << 0) |
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(bit_reverse[src[170]&3] << 2);
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dest[85] =
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(bit_reverse[src[85]&3] << 0) |
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(bit_reverse[src[171]&3] << 2);
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for(size_t c = 0; c < 256; ++c) {
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dest[86 + c] = src[c] >> 2;
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}
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// Exclusive OR each byte with the one before it.
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dest[342] = dest[341];
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size_t location = 342;
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while(location > 1) {
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--location;
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dest[location] ^= dest[location-1];
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}
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// Map six-bit values up to full bytes.
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for(size_t c = 0; c < 343; ++c) {
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dest[c] = six_and_two_mapping[dest[c]];
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}
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}
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/*!
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Converts a DSK-style track to a WOZ-style track.
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@param dest The 6646-byte buffer that will contain the WOZ track. Both track contents and the
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proper suffix will be written.
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@param src The 4096-byte buffer that contains the DSK track — 16 instances of 256 bytes, each
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a fully-decoded sector.
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@param track_number The track number to encode into this track.
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@param is_prodos @c true if the DSK image is in Pro-DOS order; @c false if it is in DOS 3.3 order.
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*/
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static void serialise_track(uint8_t *dest, const uint8_t *src, uint8_t track_number, bool is_prodos) {
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size_t track_position = 0; // This is the track position **in bits**.
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memset(dest, 0, 6646);
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// Write gap 1.
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for(size_t c = 0; c < 16; ++c) {
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track_position = write_sync(dest, track_position);
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}
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// Step through the sectors in physical order.
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for(size_t sector = 0; sector < 16; ++sector) {
|
|
/*
|
|
Write the sector header.
|
|
*/
|
|
|
|
// Prologue.
|
|
track_position = write_byte(dest, track_position, 0xd5);
|
|
track_position = write_byte(dest, track_position, 0xaa);
|
|
track_position = write_byte(dest, track_position, 0x96);
|
|
|
|
// Volume, track, setor and checksum, all in 4-and-4 format.
|
|
track_position = write_4_and_4(dest, track_position, 254);
|
|
track_position = write_4_and_4(dest, track_position, track_number);
|
|
track_position = write_4_and_4(dest, track_position, sector);
|
|
track_position = write_4_and_4(dest, track_position, 254 ^ track_number ^ sector);
|
|
|
|
// Epilogue.
|
|
track_position = write_byte(dest, track_position, 0xde);
|
|
track_position = write_byte(dest, track_position, 0xaa);
|
|
track_position = write_byte(dest, track_position, 0xeb);
|
|
|
|
|
|
// Write gap 2.
|
|
for(size_t c = 0; c < 7; ++c) {
|
|
track_position = write_sync(dest, track_position);
|
|
}
|
|
|
|
/*
|
|
Write the sector body.
|
|
*/
|
|
|
|
// Prologue.
|
|
track_position = write_byte(dest, track_position, 0xd5);
|
|
track_position = write_byte(dest, track_position, 0xaa);
|
|
track_position = write_byte(dest, track_position, 0xad);
|
|
|
|
// Map from this physical sector to a logical sector.
|
|
const int logical_sector = (sector == 15) ? 15 : ((sector * (is_prodos ? 8 : 7)) % 15);
|
|
|
|
// Sector contents.
|
|
uint8_t contents[343];
|
|
encode_6_and_2(contents, &src[logical_sector * 256]);
|
|
for(size_t c = 0; c < sizeof(contents); ++c) {
|
|
track_position = write_byte(dest, track_position, contents[c]);
|
|
}
|
|
|
|
// Epilogue.
|
|
track_position = write_byte(dest, track_position, 0xde);
|
|
track_position = write_byte(dest, track_position, 0xaa);
|
|
track_position = write_byte(dest, track_position, 0xeb);
|
|
|
|
// Write gap 3.
|
|
for(size_t c = 0; c < 16; ++c) {
|
|
track_position = write_sync(dest, track_position);
|
|
}
|
|
}
|
|
|
|
// Add the track suffix.
|
|
dest[6646] = ((track_position + 7) >> 3) & 0xff;
|
|
dest[6647] = ((track_position + 7) >> 11) & 0xff; // Byte count.
|
|
dest[6648] = track_position & 0xff;
|
|
dest[6649] = (track_position >> 8) & 0xff; // Bit count.
|
|
dest[6650] = dest[6651] = 0x00; // Splice information.
|
|
dest[6652] = 0xff;
|
|
dest[6653] = 10;
|
|
}
|