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use a function to nybblize sector

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Brad Grantham 2020-12-11 22:02:52 -08:00
parent ba52591064
commit d20991ae8e
1 changed files with 86 additions and 80 deletions
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apple2e.cpp
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@ -266,101 +266,107 @@ struct backed_region : region
const region io_region = {"io", 0xC000, 0x100}; const region io_region = {"io", 0xC000, 0x100};
unsigned char floppy_header[21] = { const unsigned char floppy_sectorHeader[21] = {
0xD5, 0xAA, 0x96, 0xFF, 0xFE, 0x00, 0x00, 0x00, 0xD5, 0xAA, 0x96, 0xFF, 0xFE, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0xDE, 0xAA, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0xDE, 0xAA, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xD5, 0xAA, 0xAD }; 0xFF, 0xFF, 0xD5, 0xAA, 0xAD };
unsigned char floppy_doSector[16] = { const unsigned char floppy_doSector[16] = {
0x0, 0x7, 0xE, 0x6, 0xD, 0x5, 0xC, 0x4, 0xB, 0x3, 0xA, 0x2, 0x9, 0x1, 0x8, 0xF }; 0x0, 0x7, 0xE, 0x6, 0xD, 0x5, 0xC, 0x4, 0xB, 0x3, 0xA, 0x2, 0x9, 0x1, 0x8, 0xF };
unsigned char floppy_poSector[16] = { const unsigned char floppy_poSector[16] = {
0x0, 0x8, 0x1, 0x9, 0x2, 0xA, 0x3, 0xB, 0x4, 0xC, 0x5, 0xD, 0x6, 0xE, 0x7, 0xF }; 0x0, 0x8, 0x1, 0x9, 0x2, 0xA, 0x3, 0xB, 0x4, 0xC, 0x5, 0xD, 0x6, 0xE, 0x7, 0xF };
const unsigned char floppy_sectorFooter[48] = {
0xDE, 0xAA, 0xEB, 0xFF, 0xEB, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
const unsigned char floppy_6BitsToBytes[0x40] = {
0x96, 0x97, 0x9A, 0x9B, 0x9D, 0x9E, 0x9F, 0xA6,
0xA7, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB2, 0xB3,
0xB4, 0xB5, 0xB6, 0xB7, 0xB9, 0xBA, 0xBB, 0xBC,
0xBD, 0xBE, 0xBF, 0xCB, 0xCD, 0xCE, 0xCF, 0xD3,
0xD6, 0xD7, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE,
0xDF, 0xE5, 0xE6, 0xE7, 0xE9, 0xEA, 0xEB, 0xEC,
0xED, 0xEE, 0xEF, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6,
0xF7, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF };
void floppy_NybblizeImage(const unsigned char *image, unsigned char *nybblized, unsigned char *skew) constexpr size_t floppy_trackGapSize = 64;
constexpr size_t nybblizedSectorSize = 21 + 343 + 48;
constexpr size_t nybblizedTrackSize = floppy_trackGapSize + 16 * nybblizedSectorSize;
void nybblizeSector(int trackIndex, int sectorIndex, const uint8_t *sectorBytes, uint8_t *sectorNybblized)
{ {
// Format of a sector is header (23) + nybbles (343) + footer (30) = 396 memset(sectorNybblized, 0xFF, nybblizedSectorSize); // Doesn't matter if 00s or FFs...
// (short by 20 bytes of 416 [413 if 48 byte header is one time only])
// hdr (21) + nybbles (343) + footer (48) = 412 bytes per sector
// (not incl. 64 byte track marker)
static unsigned char footer[48] = { uint8_t *p = sectorNybblized;
0xDE, 0xAA, 0xEB, 0xFF, 0xEB, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
static unsigned char diskbyte[0x40] = { memcpy(p, floppy_sectorHeader, sizeof(floppy_sectorHeader)); // Set up the sectorIndex header
0x96, 0x97, 0x9A, 0x9B, 0x9D, 0x9E, 0x9F, 0xA6,
0xA7, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB2, 0xB3,
0xB4, 0xB5, 0xB6, 0xB7, 0xB9, 0xBA, 0xBB, 0xBC,
0xBD, 0xBE, 0xBF, 0xCB, 0xCD, 0xCE, 0xCF, 0xD3,
0xD6, 0xD7, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE,
0xDF, 0xE5, 0xE6, 0xE7, 0xE9, 0xEA, 0xEB, 0xEC,
0xED, 0xEE, 0xEF, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6,
0xF7, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF };
memset(nybblized, 0xFF, 232960); // Doesn't matter if 00s or FFs... p[5] = ((trackIndex >> 1) & 0x55) | 0xAA;
p[6] = (trackIndex & 0x55) | 0xAA;
p[7] = ((sectorIndex >> 1) & 0x55) | 0xAA;
p[8] = (sectorIndex & 0x55) | 0xAA;
p[9] = (((trackIndex ^ sectorIndex ^ 0xFE) >> 1) & 0x55) | 0xAA;
p[10] = ((trackIndex ^ sectorIndex ^ 0xFE) & 0x55) | 0xAA;
unsigned char *p = nybblized; p += 21;
for(unsigned char trk=0; trk<35; trk++) // Convert the 256 8-bit bytes into 342 6-bit bytes.
{
memset(p, 0xFF, 64); // Write gap 1, 64 bytes (self-sync)
p += 64;
for(unsigned char sector=0; sector<16; sector++) for(int i=0; i<0x56; i++)
{ {
memcpy(p, floppy_header, 21); // Set up the sector header p[i] = ((sectorBytes[(i + 0xAC) & 0xFF] & 0x01) << 7)
| ((sectorBytes[(i + 0xAC) & 0xFF] & 0x02) << 5)
| ((sectorBytes[(i + 0x56) & 0xFF] & 0x01) << 5)
| ((sectorBytes[(i + 0x56) & 0xFF] & 0x02) << 3)
| ((sectorBytes[(i + 0x00) & 0xFF] & 0x01) << 3)
| ((sectorBytes[(i + 0x00) & 0xFF] & 0x02) << 1);
}
p[5] = ((trk >> 1) & 0x55) | 0xAA; p[0x54] &= 0x3F;
p[6] = (trk & 0x55) | 0xAA; p[0x55] &= 0x3F;
p[7] = ((sector >> 1) & 0x55) | 0xAA; memcpy(p + 0x56, sectorBytes, 256);
p[8] = (sector & 0x55) | 0xAA;
p[9] = (((trk ^ sector ^ 0xFE) >> 1) & 0x55) | 0xAA;
p[10] = ((trk ^ sector ^ 0xFE) & 0x55) | 0xAA;
p += 21; // XOR the data block with itself, offset by one byte,
const unsigned char * bytes = image; // creating a 343rd byte which is used as a cheksum.
bytes += (skew[sector] * 256) + (trk * 256 * 16); p[342] = 0x00;
// Convert the 256 8-bit bytes into 342 6-bit bytes. for(int i=342; i>0; i--)
p[i] = p[i] ^ p[i - 1];
for(int i=0; i<0x56; i++) // Using a lookup table, convert the 6-bit bytes into disk bytes.
{
p[i] = ((bytes[(i + 0xAC) & 0xFF] & 0x01) << 7)
| ((bytes[(i + 0xAC) & 0xFF] & 0x02) << 5)
| ((bytes[(i + 0x56) & 0xFF] & 0x01) << 5)
| ((bytes[(i + 0x56) & 0xFF] & 0x02) << 3)
| ((bytes[(i + 0x00) & 0xFF] & 0x01) << 3)
| ((bytes[(i + 0x00) & 0xFF] & 0x02) << 1);
}
p[0x54] &= 0x3F; for(int i=0; i<343; i++)
p[0x55] &= 0x3F; p[i] = floppy_6BitsToBytes[p[i] >> 2];
memcpy(p + 0x56, bytes, 256); p += 343;
// XOR the data block with itself, offset by one byte, // Done with the nybblization, now for the epilogue...
// creating a 343rd byte which is used as a cheksum.
p[342] = 0x00; memcpy(p, floppy_sectorFooter, sizeof(floppy_sectorFooter));
// p += 48;
}
for(int i=342; i>0; i--) void floppy_NybblizeImage(const unsigned char *floppyByteImage, unsigned char *nybblizedImage, const unsigned char *skew)
p[i] = p[i] ^ p[i - 1]; {
// Format of a sector is header (23) + nybbles (343) + footer (30) = 396
// (short by 20 bytes of 416 [413 if 48 byte header is one time only])
// hdr (21) + nybbles (343) + footer (48) = 412 bytes per sector
// (not incl. 64 byte track marker)
// Using a lookup table, convert the 6-bit bytes into disk bytes. for(unsigned char trackIndex = 0; trackIndex < 35; trackIndex++)
{
unsigned char *nybblizedTrack = nybblizedImage + trackIndex * nybblizedTrackSize;
for(int i=0; i<343; i++) memset(nybblizedTrack, 0xFF, floppy_trackGapSize); // Write gap 1, 64 bytes (self-sync)
p[i] = diskbyte[p[i] >> 2];
p += 343;
// Done with the nybblization, now for the epilogue... for(unsigned char sectorIndex = 0; sectorIndex < 16; sectorIndex++)
{
memcpy(p, footer, 48); const unsigned char * sectorBytes = floppyByteImage + (skew[sectorIndex] * 256) + (trackIndex * 256 * 16);
p += 48; nybblizeSector(trackIndex, sectorIndex, sectorBytes, nybblizedTrack + sectorIndex * nybblizedSectorSize);
} }
} }
} }
// XXX readonly at this time // XXX readonly at this time
@ -420,13 +426,13 @@ struct DISKIIboard : board_base
throw "Couldn't read floppy"; throw "Couldn't read floppy";
floppy_present[number] = true; floppy_present[number] = true;
unsigned char *skew; const unsigned char *skew;
if(strcmp(name + strlen(name) - 3, ".po") == 0) { if(strcmp(name + strlen(name) - 3, ".po") == 0) {
printf("ProDOS floppy\n"); printf("ProDOS floppy\n");
skew = floppy_poSector; skew = floppy_poSector;
} } else {
else
skew = floppy_doSector; skew = floppy_doSector;
}
floppy_NybblizeImage(floppy_image[number], floppy_nybblized[number], skew); floppy_NybblizeImage(floppy_image[number], floppy_nybblized[number], skew);
} }
} }
@ -439,26 +445,26 @@ struct DISKIIboard : board_base
{ {
std::copy(diskII_rom, diskII_rom + 0x100, rom_C600.memory.begin()); std::copy(diskII_rom, diskII_rom + 0x100, rom_C600.memory.begin());
if(floppy0_name) { if(floppy0_name) {
floppy_image[0] = new unsigned char[143360]; floppy_image[0] = new (std::nothrow) unsigned char[143360];
if(!floppy_image[0]) { if(!floppy_image[0]) {
throw "failed to allocate floppy_image[0]"; throw "failed to allocate floppy_image[0]";
} }
floppy_nybblized[0] = new unsigned char[232960]; floppy_nybblized[0] = new (std::nothrow) unsigned char[232960];
if(!floppy_nybblized[0]) { if(!floppy_nybblized[0]) {
throw "failed to allocate floppy_nybblized[0]"; throw "failed to allocate floppy_nybblized[0]";
} }
set_floppy(0, floppy0_name); set_floppy(0, floppy0_name);
} }
if(floppy1_name) { if(floppy1_name) {
floppy_image[1] = new unsigned char[143360]; floppy_image[1] = new (std::nothrow) unsigned char[143360];
if(!floppy_image[1]) { if(!floppy_image[1]) {
throw "failed to allocate floppy_image[1]"; throw "failed to allocate floppy_image[1]";
} }
floppy_nybblized[1] = new unsigned char[232960]; floppy_nybblized[1] = new (std::nothrow) unsigned char[232960];
if(!floppy_nybblized[1]) { if(!floppy_nybblized[1]) {
throw "failed to allocate floppy_nybblized[1]"; throw "failed to allocate floppy_nybblized[1]";
} }
set_floppy(1, floppy1_name); set_floppy(1, floppy1_name);
} }
} }