mirror of
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)
74 lines
2.6 KiB
C
74 lines
2.6 KiB
C
#ifndef PSX_TIMER1_SOURCE_CLOCK_H
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#define PSX_TIMER1_SOURCE_CLOCK_H
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#include <stdint.h>
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#include <string.h>
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/* Optional original-Octoshock timer 1 state machine. Independently expressed
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* from documented transitions; only IRQ-disabled modes are admitted. The
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* caller supplies ordered CPU, H-retrace and VBlank events. No guest memory. */
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typedef struct PsxTimer1Source {
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uint32_t mode, counter, target;
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int counting, blank;
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} PsxTimer1Source;
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static inline void timer1_source_reset(PsxTimer1Source *s) {
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memset(s,0,sizeof(*s)); s->blank=1;
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}
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static inline void timer1_source_match(PsxTimer1Source *s) {
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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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}
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static inline void timer1_source_count(PsxTimer1Source *s,uint32_t n) {
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if((s->mode&8) && !s->target && !s->counter) {
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timer1_source_match(s); return;
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}
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if(s->counting<=0 || !n) return;
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uint32_t before=s->counter;
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s->counter+=n;
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if((before<s->target && s->counter>=s->target) || s->counter>=s->target+65536u)
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timer1_source_match(s);
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if(s->counter>=65536u) {s->mode|=0x1000; s->counter&=65535u;}
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}
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static inline void timer1_source_cpu(PsxTimer1Source *s,uint32_t n) {
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if(!(s->mode&0x100)) timer1_source_count(s,n);
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}
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static inline void timer1_source_hblank(PsxTimer1Source *s,uint32_t n) {
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if(s->mode&0x100) timer1_source_count(s,n);
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}
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static inline void timer1_source_blank(PsxTimer1Source *s,int blank) {
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unsigned sync=s->mode&7;
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if(sync==1) s->counting=!blank;
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if(sync==5) s->counting=blank;
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if((sync==3 || sync==5) && s->blank && !blank) {
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s->counter=0;
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if(!s->target) timer1_source_match(s);
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}
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if(sync==7) {
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if(s->counting<0 && !s->blank && blank) s->counting=0;
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else if(!s->counting && s->blank && !blank) s->counting=1;
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}
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s->blank=blank;
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}
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static inline int timer1_source_write(PsxTimer1Source *s,unsigned reg,uint16_t v) {
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if(reg==4 && (v&0x30)) return 0; /* no IRQ phase claim */
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if(reg==0) s->counter=v;
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if(reg==4) {
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s->mode=(s->mode&0x1c00)|(v&0x3ff);s->counter=0;s->counting=1;
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if((v&7)==1) s->counting=!s->blank;
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if((v&7)==5) s->counting=s->blank;
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if((v&7)==7) s->counting=-1;
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}
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if(reg==8) s->target=v;
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if(s->counter==s->target) timer1_source_match(s);
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return 1;
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}
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static inline uint32_t timer1_source_read(PsxTimer1Source *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) {
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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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return 0;
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}
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#endif
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