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Reintroduced gap as a string of 1s, made an attempt to look up bit ordering. Still unclear on high/low versus low/high.

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This commit is contained in:
Thomas Harte 2016-10-11 08:07:51 -04:00
parent 70f004efbb
commit 4f78d693e9
2 changed files with 36 additions and 21 deletions
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55
Storage/Tape/Formats/OricTAP.cpp
View File

@ -93,6 +93,14 @@ Tape::Pulse OricTAP::virtual_get_next_pulse()
_phase_counter++; _phase_counter++;
if(_phase_counter > 12 && !next_byte) // advance after the filename-ending NULL byte if(_phase_counter > 12 && !next_byte) // advance after the filename-ending NULL byte
{
_next_phase = Gap;
}
break;
case Gap:
_phase_counter++;
if(_phase_counter == 8)
{ {
_next_phase = Data; _next_phase = Data;
} }
@ -119,12 +127,11 @@ Tape::Pulse OricTAP::virtual_get_next_pulse()
break; break;
} }
// TODO: which way round are bytes streamed?
uint8_t parity = next_byte; uint8_t parity = next_byte;
parity ^= (parity >> 4); parity ^= (parity >> 4);
parity ^= (parity >> 2); parity ^= (parity >> 2);
parity ^= (parity >> 1); // TODO: parity odd or even? parity ^= (parity >> 1);
_current_value = (uint16_t)(((uint16_t)next_byte << 1) | (7 << 10) | ((parity&1) << 9)); _current_value = (uint16_t)(((uint16_t)next_byte << 1) | ((parity&1) << 9) | (7 << 10));
} }
// In slow mode, a 0 is 4 periods of 1200 Hz, a 1 is 8 periods at 2400 Hz. // In slow mode, a 0 is 4 periods of 1200 Hz, a 1 is 8 periods at 2400 Hz.
@ -132,6 +139,7 @@ Tape::Pulse OricTAP::virtual_get_next_pulse()
// This code models fast mode. // This code models fast mode.
Tape::Pulse pulse; Tape::Pulse pulse;
pulse.length.clock_rate = 4800; pulse.length.clock_rate = 4800;
int next_bit;
switch(_phase) switch(_phase)
{ {
@ -140,25 +148,32 @@ Tape::Pulse OricTAP::virtual_get_next_pulse()
pulse.length.length = 4800; pulse.length.length = 4800;
return pulse; return pulse;
default: case Gap:
if(_current_value & 1) next_bit = 1;
{ break;
pulse.length.length = 1;
}
else
{
pulse.length.length = _pulse_counter ? 2 : 1;
}
pulse.type = _pulse_counter ? Pulse::High : Pulse::Low; // TODO
_pulse_counter ^= 1; default:
if(!_pulse_counter) next_bit = _current_value & 1;
{ break;
_current_value >>= 1;
_bit_count++;
}
return pulse;
} }
if(next_bit)
{
pulse.length.length = 1;
}
else
{
pulse.length.length = _pulse_counter ? 2 : 1;
}
pulse.type = _pulse_counter ? Pulse::High : Pulse::Low; // TODO
_pulse_counter ^= 1;
if(!_pulse_counter)
{
_current_value >>= 1;
_bit_count++;
}
return pulse;
} }
bool OricTAP::is_at_end() bool OricTAP::is_at_end()

2
Storage/Tape/Formats/OricTAP.hpp
View File

@ -48,7 +48,7 @@ class OricTAP: public Tape {
int _phase_counter; int _phase_counter;
enum Phase { enum Phase {
LeadIn, Header, Data, End LeadIn, Header, Data, Gap, End
} _phase, _next_phase; } _phase, _next_phase;
uint16_t _data_end_address, _data_start_address; uint16_t _data_end_address, _data_start_address;
}; };