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trs80: fixed loading of CAS files

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This commit is contained in:
Robbbert 2021-03-28 21:08:40 +11:00
parent bbe3ba79aa
commit 648374e435
3 changed files with 27 additions and 31 deletions
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54
src/lib/formats/trs_cas.cpp
View File

@ -15,42 +15,33 @@ Support for TRS80 .cas cassette images
#define SMPHI 32767
static int cas_size; // FIXME: global variable prevents mutliple instances
static int cas_size; // FIXME: global variable prevents multiple instances
/*******************************************************************
Generate one high-low cycle of sample data
********************************************************************/
static inline int trs80l2_cas_cycle(int16_t *buffer, int sample_pos, int silence, int high, int low)
static inline int trs80l2_cas_cycle(int16_t *buffer, int sample_pos, bool bit)
{
int i = 0;
uint8_t i;
if ( buffer )
{
while( i < silence )
{
buffer[ sample_pos + i ] = SILENCE;
i++;
}
while( i < silence + high)
{
buffer[ sample_pos + i ] = SMPHI;
i++;
}
while( i < silence + high + low )
{
buffer[ sample_pos + i ] = SMPLO;
i++;
}
for (i = 0; i < 32; i++)
buffer[ sample_pos++ ] = SILENCE;
for (i = 0; i < 6; i++)
buffer[ sample_pos++ ] = bit ? SMPHI : SILENCE;
for (i = 0; i < 6; i++)
buffer[ sample_pos++ ] = bit ? SMPLO : SILENCE;
}
return silence + high + low;
return 44;
}
static int trs80l2_handle_cas(int16_t *buffer, const uint8_t *casdata)
{
int data_pos, sample_count;
int data_pos = 0, sample_count = 0;
bool a5sw = false;
data_pos = 0;
sample_count = 0;
@ -58,24 +49,31 @@ static int trs80l2_handle_cas(int16_t *buffer, const uint8_t *casdata)
while( data_pos < cas_size )
{
uint8_t data = casdata[data_pos];
int i;
for ( i = 0; i < 8; i++ )
for (uint8_t i = 0; i < 8; i++ )
{
/* Signal code */
sample_count += trs80l2_cas_cycle( buffer, sample_count, 33, 6, 6 );
sample_count += trs80l2_cas_cycle( buffer, sample_count, true );
/* Bit code */
if ( data & 0x80 )
sample_count += trs80l2_cas_cycle( buffer, sample_count, 33, 6, 6 );
else
sample_count += trs80l2_cas_cycle( buffer, sample_count, 33 + 6 + 6, 0, 0 );
sample_count += trs80l2_cas_cycle( buffer, sample_count, data >> 7 );
data <<= 1;
}
if (!a5sw && (casdata[data_pos] == 0xA5))
{
a5sw = true;
// Need 1ms silence here while rom is busy
sample_count += trs80l2_cas_cycle( buffer, sample_count, false );
}
data_pos++;
}
// Specification requires a short silence to indicate EOF
sample_count += trs80l2_cas_cycle( buffer, sample_count, false );
sample_count += trs80l2_cas_cycle( buffer, sample_count, false );
return sample_count;
}

1
src/mame/drivers/trs80.cpp
View File

@ -155,7 +155,6 @@ lnw80: works
2021-03-26 MT 07903 - most floppies no longer boot.
Most machines have problems loading real tapes.
Cannot load CAS tapes, but they can be loaded with trs80m3.
*******************************************************************************************************/

3
src/mame/machine/trs80.cpp
View File

@ -12,8 +12,7 @@
TIMER_CALLBACK_MEMBER(trs80_state::cassette_data_callback)
{
/* This does all baud rates. 250 baud (trs80), and 500 baud (all others) set bit 7 of "cassette_data".
1500 baud (trs80m3, trs80m4) is interrupt-driven and uses bit 0 of "cassette_data" */
// This does all baud rates. 250 baud (trs80), and 500 baud (all others) set bit 7 of "cassette_data".
double new_val = (m_cassette->input());