// license:BSD-3-Clause
// copyright-holders:Olivier Galibert
#include "emu.h"
#include "fdc_pll.h"
#include "imagedev/floppy.h"
void fdc_pll_t::set_clock(const attotime &_period)
{
period = _period;
double period_as_double = period.as_double();
period_adjust_base = attotime::from_double(period_as_double * 0.05);
min_period = attotime::from_double(period_as_double * 0.75);
max_period = attotime::from_double(period_as_double * 1.25);
}
void fdc_pll_t::reset(const attotime &when)
{
read_reset(when);
write_position = 0;
write_start_time = attotime::never;
}
void fdc_pll_t::read_reset(const attotime &when)
{
ctime = when;
phase_adjust = attotime::zero;
freq_hist = 0;
}
void fdc_pll_t::start_writing(const attotime &tm)
{
write_start_time = tm;
write_position = 0;
}
void fdc_pll_t::stop_writing(floppy_image_device *floppy, const attotime &tm)
{
commit(floppy, tm);
write_start_time = attotime::never;
}
void fdc_pll_t::commit(floppy_image_device *floppy, const attotime &tm)
{
if(write_start_time.is_never() || tm == write_start_time)
return;
if(floppy)
floppy->write_flux(write_start_time, tm, write_position, write_buffer);
write_start_time = tm;
write_position = 0;
}
int fdc_pll_t::get_next_bit(attotime &tm, floppy_image_device *floppy, const attotime &limit)
{
attotime edge = floppy ? floppy->get_next_transition(ctime) : attotime::never;
return feed_read_data(tm , edge , limit);
}
int fdc_pll_t::feed_read_data(attotime &tm, const attotime& edge, const attotime &limit)
{
attotime next = ctime + period + phase_adjust;
#if 0
if(!edge.is_never())
fprintf(stderr, "%s\n", util::string_format("fdc pll ctime=%s, transition_time=%s, next=%s, pha=%s\n", ctime.to_string(), edge.to_string(), next.to_string(), phase_adjust.to_string()).c_str());
#endif
if(next > limit)
return -1;
ctime = next;
tm = next;
if(edge.is_never() || edge > next) {
// No transition in the window means 0 and pll in free run mode
phase_adjust = attotime::zero;
return 0;
}
// Transition in the window means 1, and the pll is adjusted
attotime delta = edge - (next - period/2);
if(delta.seconds() < 0)
phase_adjust = attotime::zero - ((attotime::zero - delta)*65)/100;
else
phase_adjust = (delta*65)/100;
if(delta < attotime::zero) {
if(freq_hist < 0)
freq_hist--;
else
freq_hist = -1;
} else if(delta > attotime::zero) {
if(freq_hist > 0)
freq_hist++;
else
freq_hist = 1;
} else
freq_hist = 0;
if(freq_hist) {
int afh = freq_hist < 0 ? -freq_hist : freq_hist;
if(afh > 1) {
attotime aper = attotime::from_double(period_adjust_base.as_double()*delta.as_double()/period.as_double());
period += aper;
if(period < min_period)
period = min_period;
else if(period > max_period)
period = max_period;
}
}
return 1;
}
bool fdc_pll_t::write_next_bit(bool bit, attotime &tm, floppy_image_device *floppy, const attotime &limit)
{
if(write_start_time.is_never()) {
write_start_time = ctime;
write_position = 0;
}
attotime etime = ctime + period;
if(etime > limit)
return true;
if(bit && write_position < std::size(write_buffer))
write_buffer[write_position++] = ctime + period/2;
tm = etime;
ctime = etime;
return false;
}