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Adapted pervasively to MSB-first output. Which seems to be correct.

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This commit is contained in:
Thomas Harte 2016-09-18 18:46:58 -04:00
parent 5ebca62bba
commit d9aaf456f0
1 changed files with 25 additions and 21 deletions
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46
Storage/Disk/Encodings/MFM.cpp
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@ -22,7 +22,10 @@ template <class T> class Shifter {
virtual void add_deleted_data_address_mark() = 0;
protected:
// override me!
/*!
Intended to be overridden by subclasses; should write value out as PCM data,
MSB first.
*/
void output_short(uint16_t value);
};
@ -70,40 +73,41 @@ template <class T> class MFMShifter: public Shifter<T> {
};
template <class T> class FMShifter: public Shifter<T> {
// encodes each 16-bit part as clock, data, clock, data [...]
public:
void add_byte(uint8_t input) {
static_cast<T *>(this)->output_short(
(uint16_t)(
((input & 0x01) << 1) |
((input & 0x02) << 2) |
((input & 0x04) << 3) |
((input & 0x08) << 4) |
((input & 0x10) << 5) |
((input & 0x20) << 6) |
((input & 0x40) << 7) |
((input & 0x80) << 8) |
0x5555
((input & 0x01) << 0) |
((input & 0x02) << 1) |
((input & 0x04) << 2) |
((input & 0x08) << 3) |
((input & 0x10) << 4) |
((input & 0x20) << 5) |
((input & 0x40) << 6) |
((input & 0x80) << 7) |
0xaaaa
));
}
void add_index_address_mark() {
// data 0xfc, with clock 0xd7 => 1111 1100 with clock 1101 0111 => 1111 1011 1011 0101
static_cast<T *>(this)->output_short(0xfbb5);
// data 0xfc, with clock 0xd7 => 1111 1100 with clock 1101 0111 => 1111 0111 0111 1010
static_cast<T *>(this)->output_short(0xf77a);
}
void add_ID_address_mark() {
// data 0xfe, with clock 0xc7 => 1111 1110 with clock 1100 0111 => 1111 1010 1011 1101
static_cast<T *>(this)->output_short(0xfabd);
// data 0xfe, with clock 0xc7 => 1111 1110 with clock 1100 0111 => 1111 0101 0111 1110
static_cast<T *>(this)->output_short(0xf57e);
}
void add_data_address_mark() {
// data 0xfb, with clock 0xc7 => 1111 1011 with clock 1100 0111 => 1111 1010 1001 1111
static_cast<T *>(this)->output_short(0xfa9f);
// data 0xfb, with clock 0xc7 => 1111 1011 with clock 1100 0111 => 1111 0101 0110 1111
static_cast<T *>(this)->output_short(0xf56f);
}
void add_deleted_data_address_mark() {
// data 0xf8, with clock 0xc7 => 1111 1000 with clock 1100 0111 => 1111 1010 1001 0101
static_cast<T *>(this)->output_short(0xfa95);
// data 0xf8, with clock 0xc7 => 1111 1000 with clock 1100 0111 => 1111 0101 0110 1010
static_cast<T *>(this)->output_short(0xf56a);
}
};
@ -158,8 +162,8 @@ template<class T> std::shared_ptr<Storage::Disk::Track>
crc_generator.add(sector.sector);
crc_generator.add(size);
uint16_t crc_value = crc_generator.get_value();
shifter.add_byte(crc_value & 0xff);
shifter.add_byte(crc_value >> 8);
shifter.add_byte(crc_value & 0xff);
// gap
for(int c = 0; c < post_address_mark_bytes; c++) shifter.add_byte(0x4e);
@ -176,8 +180,8 @@ template<class T> std::shared_ptr<Storage::Disk::Track>
// data CRC
crc_value = crc_generator.get_value();
shifter.add_byte(crc_value & 0xff);
shifter.add_byte(crc_value >> 8);
shifter.add_byte(crc_value & 0xff);
// gap
for(int c = 0; c < post_data_bytes; c++) shifter.add_byte(0x00);
@ -192,8 +196,8 @@ template<class T> std::shared_ptr<Storage::Disk::Track>
struct VectorReceiver {
void output_short(uint16_t value) {
data.push_back(value & 0xff);
data.push_back(value >> 8);
data.push_back(value & 0xff);
}
std::vector<uint8_t> data;
};