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This possibly correctly encapsultes the lowest level of FM and MFM rules.

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This commit is contained in:
Thomas Harte 2016-09-18 14:17:06 -04:00
parent bcf91de7e9
commit 0089c830c6
2 changed files with 85 additions and 47 deletions
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39
Storage/Disk/Encodings/MFM.cpp
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@ -9,42 +9,3 @@
#include "MFM.hpp" #include "MFM.hpp"
using namespace Storage::Encodings; using namespace Storage::Encodings;
void Shifter::add_sync()
{
// i.e. 0100 0100 1000 1001
output = (uint16_t)((output << 15) | 0x4489);
}
void MFMShifter::shift(uint8_t input)
{
uint16_t spread_value =
(uint16_t)(
((input & 0x01) << 0) |
((input & 0x02) << 1) |
((input & 0x04) << 2) |
((input & 0x08) << 3) |
((input & 0x10) << 4) |
((input & 0x20) << 5) |
((input & 0x40) << 6) |
((input & 0x80) << 7)
);
uint16_t or_bits = (uint16_t)((spread_value << 1) | (spread_value >> 1) | (output << 15));
output = spread_value | ((~or_bits) & 0xaaaa);
}
void FMShifter::shift(uint8_t input)
{
output =
(uint16_t)(
((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
);
}

93
Storage/Disk/Encodings/MFM.hpp
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@ -14,21 +14,98 @@
namespace Storage { namespace Storage {
namespace Encodings { namespace Encodings {
class Shifter { template <class T> class Shifter {
public: public:
virtual void shift(uint8_t input) = 0; virtual void add_byte(uint8_t input) = 0;
void add_sync(); virtual void add_index_address_mark() = 0;
uint16_t output; virtual void add_ID_address_mark() = 0;
virtual void add_data_address_mark() = 0;
virtual void add_deleted_data_address_mark() = 0;
protected:
// override me!
void output_short(uint16_t value);
}; };
class MFMShifter: public Shifter { template <class T> class MFMShifter: public Shifter<T> {
public: public:
void shift(uint8_t input); void add_byte(uint8_t input) {
uint16_t spread_value =
(uint16_t)(
((input & 0x01) << 0) |
((input & 0x02) << 1) |
((input & 0x04) << 2) |
((input & 0x08) << 3) |
((input & 0x10) << 4) |
((input & 0x20) << 5) |
((input & 0x40) << 6) |
((input & 0x80) << 7)
);
uint16_t or_bits = (uint16_t)((spread_value << 1) | (spread_value >> 1) | (output_ << 15));
output_ = spread_value | ((~or_bits) & 0xaaaa);
static_cast<T *>(this)->output_short(output_);
}
void add_index_address_mark() {
static_cast<T *>(this)->output_short(output_ = 0x5224);
add_byte(0xfc);
}
void add_ID_address_mark() {
static_cast<T *>(this)->output_short(output_ = 0x4489);
add_byte(0xfe);
}
void add_data_address_mark() {
static_cast<T *>(this)->output_short(output_ = 0x4489);
add_byte(0xfb);
}
void add_deleted_data_address_mark() {
static_cast<T *>(this)->output_short(output_ = 0x4489);
add_byte(0xf8);
}
private:
uint16_t output_;
}; };
class FMShifter: public Shifter { template <class T> class FMShifter: public Shifter<T> {
public: public:
void shift(uint8_t input); 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
));
}
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);
}
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);
}
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);
}
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);
}
}; };
} }