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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)
79 lines
3.1 KiB
C
79 lines
3.1 KiB
C
#ifndef PSX_TIMER2_SOURCE_CLOCK_H
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#define PSX_TIMER2_SOURCE_CLOCK_H
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#include <stdint.h>
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#include <string.h>
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/* Explicit original-Octoshock compatibility state. Independent expression of
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* the retained source transitions, qualified against an external scalar oracle.
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* This is not a claim that every original-core quirk describes PS1 hardware.
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* No guest memory, title addresses, input words or selected timing constants. */
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typedef struct PsxTimer2Source {
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uint32_t counter,mode,target,divider;
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int irq_done,counting;
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} PsxTimer2Source;
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static inline void timer2_source_reset(PsxTimer2Source *s){memset(s,0,sizeof(*s));}
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static inline int timer2_source_target(PsxTimer2Source *s,unsigned *pulses){
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s->mode|=0x800;
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if(s->mode&8) s->counter%=s->target?s->target:1;
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if(!(s->mode&0x10) || s->irq_done) return 0;
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s->irq_done=1;(*pulses)++;
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return !s->counter || s->counter==s->target;
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}
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static inline unsigned timer2_source_cpu(PsxTimer2Source *s,uint32_t cycles){
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unsigned pulses=0;
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/* Original TIMER_Update skips this encoding even for timer 2. */
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if(s->mode&0x100) return 0;
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if(s->counting<=0) cycles=0;
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uint32_t divided=(s->divider+cycles)>>3;
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s->divider=(s->divider+cycles)&7;
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if(s->mode&0x200) cycles=divided;
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if(s->mode&1) cycles=0;
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if((s->mode&8) && !s->target && !s->counter){
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(void)timer2_source_target(s,&pulses);return pulses;
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}
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if(!cycles) return 0;
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uint32_t before=s->counter;
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s->counter+=cycles;
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if(s->mode&0x40) s->irq_done=0;
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int exact=0;
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if((before<s->target && s->counter>=s->target) || s->counter>=s->target+65536u)
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exact=timer2_source_target(s,&pulses);
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if(s->counter>=65536u){
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s->mode|=0x1000;s->counter&=65535u;
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if((s->mode&0x20) && !s->irq_done){
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exact|=!s->counter;s->irq_done=1;pulses++;
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}
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}
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if((s->mode&0x40) && !exact) s->irq_done=0;
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return pulses;
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}
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static inline unsigned timer2_source_write(PsxTimer2Source *s,unsigned reg,uint16_t v){
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unsigned pulses=0;
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if(reg==0){s->counter=v;s->irq_done=0;}
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if(reg==4){
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s->mode=(s->mode&0x1c00)|(v&0x3ff);s->counter=0;s->irq_done=0;
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s->counting=1; /* Divider deliberately survives mode writes. */
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}
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if(reg==8) s->target=v;
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if(s->counter==s->target)(void)timer2_source_target(s,&pulses);
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return pulses;
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}
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static inline uint32_t timer2_source_read(PsxTimer2Source *s,unsigned reg){
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if(reg==0)return s->counter;
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if(reg==8)return s->target;
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if(reg!=4)return 0;
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uint32_t value=s->mode;s->mode&=~0x1000u;
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if(s->counter!=s->target)s->mode&=~0x800u;
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return value;
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}
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static inline uint32_t timer2_source_next(const PsxTimer2Source *s){
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/* Source periodic update bound, independent of CPU interrupt masking. */
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if(!(s->mode&0x30))return 1024;
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if((s->mode&8) && !s->counter && !s->target && !s->irq_done)return 1;
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if((s->mode&1) || s->counting<=0)return 1024;
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uint32_t target=((s->mode&0x18) && s->counter<s->target)?s->target:65536u;
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uint32_t clocks=target-s->counter;
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if(s->mode&0x200)clocks=clocks*8-s->divider;
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return clocks<1024?clocks:1024;
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}
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#endif
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