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https://github.com/RetroPortingToolKit/psxrecomp
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Pegasus
3bd62b3099
Rebased onto upstream after #362: the Ape Escape card-repair hunks are
dropped with the removed block, and the pace walk keeps upstream's uncapped
deadline consumption plus the source ACK-pulse edge.
(cherry picked from commit 8235a7700f)
44 lines
1.8 KiB
C
44 lines
1.8 KiB
C
#ifndef PSX_INPUT_ROUTE_FIELD_CLOCK_H
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#define PSX_INPUT_ROUTE_FIELD_CLOCK_H
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#include <stdint.h>
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/* Cold-boot comparison clock, independent of guest memory and input contents.
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* Behavioral constants: original Octoshock 2.2.2 GPU, NTSC hardware clock
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* ratio 103896/65536; alternating 3412/3413 GPU clocks per scanline;
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* 263 progressive lines, 263/262 interlaced lines. This is a field-duration
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* profile, not its complete scanline/IRQ/CPU timing implementation.
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* Independently written arithmetic; no reference implementation copied.
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*/
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typedef struct InputRouteFieldClock {
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uint32_t remainder;
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uint32_t line_phase;
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uint32_t field;
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uint32_t current_cycles;
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} InputRouteFieldClock;
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static inline void input_route_field_clock_select(InputRouteFieldClock *s,
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int interlaced) {
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uint32_t lines = interlaced ? 263u - s->field : 263u;
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uint32_t gpu_clocks = lines * 3412u + (lines + s->line_phase) / 2u;
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uint64_t numerator = (uint64_t)gpu_clocks * 65536u;
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/* Keep cumulative deadlines at ceil(total GPU clocks / clock ratio).
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* Represent the remainder as unused fractional CPU-cycle credit. */
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numerator -= s->remainder;
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s->current_cycles = (uint32_t)((numerator + 103895u) / 103896u);
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s->remainder = (uint32_t)((uint64_t)s->current_cycles * 103896u - numerator);
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s->line_phase = (s->line_phase + lines) & 1u;
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}
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static inline void input_route_field_clock_reset(InputRouteFieldClock *s) {
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s->remainder = s->line_phase = s->field = 0u;
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input_route_field_clock_select(s, 0);
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}
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static inline void input_route_field_clock_next(InputRouteFieldClock *s,
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int interlaced) {
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s->field = interlaced ? !s->field : 0u;
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input_route_field_clock_select(s, interlaced);
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}
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#endif
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