Mac encoder is code-complete.

arch/macintosh/encoder.cc

@@ -21,12 +21,14 @@ static bool lastBit;
 static double clockRateUsForTrack(unsigned track)
 {
 	if (track < 16)
-		return 2.65;
+		return 2.623;
 	if (track < 32)
-		return 2.90;
+		return 2.861;
 	if (track < 48)
-		return 3.20;
-	return 4.00;
+		return 3.148;
+	if (track < 64)
+		return 3.497;
+	return 3.934;
 }
 
 static unsigned sectorsForTrack(unsigned track)
@@ -37,7 +39,170 @@ static unsigned sectorsForTrack(unsigned track)
 		return 11;
 	if (track < 48)
 		return 10;
-	return 9;
+	if (track < 64)
+		return 9;
+	return 8;
+}
+
+static int encode_data_gcr(uint8_t gcr)
+{
+    switch (gcr)
+    {
+		#define GCR_ENTRY(gcr, data) \
+			case data: return gcr;
+		#include "data_gcr.h"
+		#undef GCR_ENTRY
+    }
+    return -1;
+};
+
+/* This is extremely inspired by the MESS implementation, written by Nathan Woods
+ * and R. Belmont: https://github.com/mamedev/mame/blob/4263a71e64377db11392c458b580c5ae83556bc7/src/lib/formats/ap_dsk35.cpp
+ */
+static Bytes encode_crazy_data(const Bytes& input)
+{
+    Bytes output;
+    ByteWriter bw(output);
+    ByteReader br(input);
+
+	uint8_t w1, w2, w3, w4;
+
+    static const int LOOKUP_LEN = MAC_SECTOR_LENGTH / 3;
+
+    uint8_t b1[LOOKUP_LEN + 1];
+    uint8_t b2[LOOKUP_LEN + 1];
+    uint8_t b3[LOOKUP_LEN + 1];
+
+	uint32_t c1 = 0;
+	uint32_t c2 = 0;
+	uint32_t c3 = 0;
+	for (int j=0;; j++)
+	{
+		c1 = (c1 & 0xff) << 1;
+		if (c1 & 0x0100)
+			c1++;
+
+		uint8_t val = br.read_8();
+		c3 += val;
+		if (c1 & 0x0100)
+		{
+			c3++;
+			c1 &= 0xff;
+		}
+		b1[j] = (val ^ c1) & 0xff;
+
+		val = br.read_8();
+		c2 += val;
+		if (c3 > 0xff)
+		{
+			c2++;
+			c3 &= 0xff;
+		}
+		b2[j] = (val ^ c3) & 0xff;
+
+		if (br.pos == 524)
+			break;
+
+		val = br.read_8();
+		c1 += val;
+		if (c2 > 0xff)
+		{
+			c1++;
+			c2 &= 0xff;
+		}
+		b3[j] = (val ^ c2) & 0xff;
+	}
+	uint32_t c4 = ((c1 & 0xc0) >> 6) | ((c2 & 0xc0) >> 4) | ((c3 & 0xc0) >> 2);
+	b3[LOOKUP_LEN] = 0;
+
+	for (int i = 0; i <= LOOKUP_LEN; i++)
+	{
+		w1 = b1[i] & 0x3f;
+		w2 = b2[i] & 0x3f;
+		w3 = b3[i] & 0x3f;
+		w4 =  ((b1[i] & 0xc0) >> 2);
+		w4 |= ((b2[i] & 0xc0) >> 4);
+		w4 |= ((b3[i] & 0xc0) >> 6);
+
+		bw.write_8(w4);
+		bw.write_8(w1);
+		bw.write_8(w2);
+
+		if (i != LOOKUP_LEN)
+			bw.write_8(w3);
+	}
+
+	bw.write_8(c1 & 0x3f);
+	bw.write_8(c2 & 0x3f);
+	bw.write_8(c3 & 0x3f);
+	bw.write_8(c4 & 0x3f);
+
+	return output;
+}
+
+static void write_bits(std::vector<bool>& bits, unsigned& cursor, const std::vector<bool>& src)
+{
+	for (bool bit : src)
+	{
+		if (cursor < bits.size())
+			bits[cursor++] = bit;
+	}
+}
+
+static void write_bits(std::vector<bool>& bits, unsigned& cursor, uint64_t data, int width)
+{
+	cursor += width;
+	for (int i=0; i<width; i++)
+	{
+		unsigned pos = cursor - i - 1;
+		if (pos < bits.size())
+			bits[pos] = data & 1;
+		data >>= 1;
+	}
+}
+
+static uint8_t encode_side(uint8_t track, uint8_t side)
+{
+    /* Mac disks, being weird, use the side byte to encode both the side (in
+     * bit 5) and also whether we're above track 0x3f (in bit 6).
+     */
+
+	return (side ? 0x20 : 0x00) | ((track>0x3f) ? 0x01 : 0x00);
+}
+
+static void write_sector(std::vector<bool>& bits, unsigned& cursor, const Sector* sector)
+{
+	if ((sector->data.size() != 512) && (sector->data.size() != 524))
+		Error() << "unsupported sector size --- you must pick 512 or 524";
+
+	write_bits(bits, cursor, 0xff, 1*8); /* pad byte */
+	for (int i=0; i<7; i++)
+		write_bits(bits, cursor, 0xff3fcff3fcffLL, 6*8); /* sync */
+	write_bits(bits, cursor, MAC_SECTOR_RECORD, 3*8);
+
+    uint8_t encodedTrack = sector->physicalTrack & 0x3f;
+	uint8_t encodedSector = sector->logicalSector;
+	uint8_t encodedSide = encode_side(sector->physicalTrack, sector->logicalSide);
+	uint8_t formatByte = MAC_FORMAT_BYTE;
+	uint8_t headerChecksum = (encodedTrack ^ encodedSector ^ encodedSide ^ formatByte) & 0x3f;
+
+	write_bits(bits, cursor, encode_data_gcr(encodedTrack), 1*8);
+	write_bits(bits, cursor, encode_data_gcr(encodedSector), 1*8);
+	write_bits(bits, cursor, encode_data_gcr(encodedSide), 1*8);
+	write_bits(bits, cursor, encode_data_gcr(formatByte), 1*8);
+	write_bits(bits, cursor, encode_data_gcr(headerChecksum), 1*8);
+
+	write_bits(bits, cursor, 0xdeaaff, 3*8);
+	write_bits(bits, cursor, 0xff3fcff3fcffLL, 6*8); /* sync */
+	write_bits(bits, cursor, MAC_DATA_RECORD, 3*8);
+	write_bits(bits, cursor, encode_data_gcr(sector->logicalSector), 1*8);
+
+	Bytes wireData;
+	wireData.writer().append(sector->data.slice(512, 12)).append(sector->data.slice(0, 512));
+	for (uint8_t b : encode_crazy_data(wireData))
+		write_bits(bits, cursor, encode_data_gcr(b), 1*8);
+
+	write_bits(bits, cursor, 0xdeaaff, 3*8);
 }
 
 std::unique_ptr<Fluxmap> MacintoshEncoder::encode(
@@ -58,12 +223,12 @@ std::unique_ptr<Fluxmap> MacintoshEncoder::encode(
 	for (int sectorId=0; sectorId<numSectors; sectorId++)
 	{
 		const auto& sectorData = allSectors.get(physicalTrack, physicalSide, sectorId);
-		//write_sector(bits, cursor, sectorData);
+		write_sector(bits, cursor, sectorData);
     }
 
 	if (cursor >= bits.size())
-		Error() << "track data overrun";
-	fillBitmapTo(bits, cursor, bits.size(), { true, false });
+		Error() << fmt::format("track data overrun by {} bits", cursor - bits.size());
+	//fillBitmapTo(bits, cursor, bits.size(), { true, false });
 
 	std::unique_ptr<Fluxmap> fluxmap(new Fluxmap);
 	fluxmap->appendBits(bits, clockRateUs*1e3);