Mechanical refactor to rearrange the source files into a more pleasing order.

2025-10-31 11:17:01 -07:00 · 2019-08-06 22:25:11 +02:00
parent 5748f017dd
commit 4b07c38782
35 changed files with 14 additions and 14 deletions
--- a/arch/apple2/decoder.cc
+++ b/arch/apple2/decoder.cc
@@ -0,0 +1,112 @@
+#include "globals.h"
+#include "fluxmap.h"
+#include "decoders/fluxmapreader.h"
+#include "protocol.h"
+#include "record.h"
+#include "decoders/decoders.h"
+#include "sector.h"
+#include "apple2.h"
+#include "bytes.h"
+#include "fmt/format.h"
+#include <string.h>
+#include <algorithm>
+
+const FluxPattern SECTOR_RECORD_PATTERN(24, APPLE2_SECTOR_RECORD);
+const FluxPattern DATA_RECORD_PATTERN(24, APPLE2_DATA_RECORD);
+const FluxMatchers ANY_RECORD_PATTERN({ &SECTOR_RECORD_PATTERN, &DATA_RECORD_PATTERN });
+
+static int decode_data_gcr(uint8_t gcr)
+{
+    switch (gcr)
+    {
+		#define GCR_ENTRY(gcr, data) \
+			case gcr: return data;
+		#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/7914a6083a3b3a8c243ae6c3b8cb50b023f21e0e/src/lib/formats/ap2_dsk.cpp
+ */
+static Bytes decode_crazy_data(const uint8_t* inp, Sector::Status& status)
+{
+    Bytes output(APPLE2_SECTOR_LENGTH);
+
+    uint8_t checksum = 0;
+    for (unsigned i = 0; i < APPLE2_ENCODED_SECTOR_LENGTH; i++)
+    {
+        checksum ^= decode_data_gcr(*inp++);
+
+        if (i >= 86)
+        {
+            /* 6 bit */
+            output[i - 86] |= (checksum << 2);
+        }
+        else
+        {
+            /* 3 * 2 bit */
+            output[i + 0] = ((checksum >> 1) & 0x01) | ((checksum << 1) & 0x02);
+            output[i + 86] = ((checksum >> 3) & 0x01) | ((checksum >> 1) & 0x02);
+            if ((i + 172) < APPLE2_SECTOR_LENGTH)
+                output[i + 172] = ((checksum >> 5) & 0x01) | ((checksum >> 3) & 0x02);
+        }
+    }
+
+    checksum &= 0x3f;
+    uint8_t wantedchecksum = decode_data_gcr(*inp);
+    status = (checksum == wantedchecksum) ? Sector::OK : Sector::BAD_CHECKSUM;
+    return output;
+}
+
+uint8_t combine(uint16_t word)
+{
+    return word & (word >> 7);
+}
+
+AbstractDecoder::RecordType Apple2Decoder::advanceToNextRecord()
+{
+	const FluxMatcher* matcher = nullptr;
+	_sector->clock = _fmr->seekToPattern(ANY_RECORD_PATTERN, matcher);
+	if (matcher == &SECTOR_RECORD_PATTERN)
+		return RecordType::SECTOR_RECORD;
+	if (matcher == &DATA_RECORD_PATTERN)
+		return RecordType::DATA_RECORD;
+	return RecordType::UNKNOWN_RECORD;
+}
+
+void Apple2Decoder::decodeSectorRecord()
+{
+    /* Skip ID (as we know it's a APPLE2_SECTOR_RECORD). */
+    readRawBits(24);
+
+    /* Read header. */
+
+    auto header = toBytes(readRawBits(8*8)).slice(0, 8);
+    ByteReader br(header);
+
+    uint8_t volume = combine(br.read_be16());
+    _sector->logicalTrack = combine(br.read_be16());
+    _sector->logicalSector = combine(br.read_be16());
+    uint8_t checksum = combine(br.read_be16());
+    if (checksum == (volume ^ _sector->logicalTrack ^ _sector->logicalSector))
+        _sector->status = Sector::DATA_MISSING; /* unintuitive but correct */
+}
+
+void Apple2Decoder::decodeDataRecord()
+{
+    /* Check ID. */
+
+    Bytes bytes = toBytes(readRawBits(3*8)).slice(0, 3);
+    if (bytes.reader().read_be24() != APPLE2_DATA_RECORD)
+        return;
+
+    /* Read and decode data. */
+
+    unsigned recordLength = APPLE2_ENCODED_SECTOR_LENGTH + 2;
+    bytes = toBytes(readRawBits(recordLength*8)).slice(0, recordLength);
+
+    _sector->status = Sector::BAD_CHECKSUM;
+    _sector->data = decode_crazy_data(&bytes[0], _sector->status);
+}