1 // PC Engine CPU emulator for use with HES music files
2
3 // $package
4 #ifndef HES_CPU_H
5 #define HES_CPU_H
6
7 #include "blargg_common.h"
8
9 class Hes_Cpu {
10 public:
11 typedef BOOST::uint8_t byte;
12 typedef int time_t;
13 typedef int addr_t;
14 enum { future_time = INT_MAX/2 + 1 };
15
16 void reset();
17
18 enum { page_bits = 13 };
19 enum { page_size = 1 << page_bits };
20 enum { page_count = 0x10000 / page_size };
21 void set_mmr( int reg, int bank, void const* code );
22
23 byte const* get_code( addr_t );
24
25 // NOT kept updated during emulation.
26 struct registers_t {
27 BOOST::uint16_t pc;
28 byte a;
29 byte x;
30 byte y;
31 byte flags;
32 byte sp;
33 };
34 registers_t r;
35
36 // page mapping registers
37 byte mmr [page_count + 1];
38
39 // Time of beginning of next instruction to be executed
time()40 time_t time() const { return cpu_state->time + cpu_state->base; }
set_time(time_t t)41 void set_time( time_t t ) { cpu_state->time = t - cpu_state->base; }
adjust_time(int delta)42 void adjust_time( int delta ) { cpu_state->time += delta; }
43
44 // Clocks past end (negative if before)
time_past_end()45 int time_past_end() const { return cpu_state->time; }
46
47 // Time of next IRQ
irq_time()48 time_t irq_time() const { return irq_time_; }
49 void set_irq_time( time_t );
50
51 // Emulation stops once time >= end_time
end_time()52 time_t end_time() const { return end_time_; }
53 void set_end_time( time_t );
54
55 // Subtracts t from all times
56 void end_frame( time_t t );
57
58 // Can read this many bytes past end of a page
59 enum { cpu_padding = 8 };
60
61 private:
62 // noncopyable
63 Hes_Cpu( const Hes_Cpu& );
64 Hes_Cpu& operator = ( const Hes_Cpu& );
65
66
67 // Implementation
68 public:
Hes_Cpu()69 Hes_Cpu() { cpu_state = &cpu_state_; }
70 enum { irq_inhibit_mask = 0x04 };
71
72 struct cpu_state_t {
73 byte const* code_map [page_count + 1];
74 time_t base;
75 int time;
76 };
77 cpu_state_t* cpu_state; // points to cpu_state_ or a local copy
78 cpu_state_t cpu_state_;
79 time_t irq_time_;
80 time_t end_time_;
81
82 private:
83 void set_code_page( int, void const* );
84 inline void update_end_time( time_t end, time_t irq );
85 };
86
87 #define HES_CPU_PAGE( addr ) ((unsigned) (addr) >> Hes_Cpu::page_bits)
88
89 #if BLARGG_NONPORTABLE
90 #define HES_CPU_OFFSET( addr ) (addr)
91 #else
92 #define HES_CPU_OFFSET( addr ) ((addr) & (Hes_Cpu::page_size - 1))
93 #endif
94
get_code(addr_t addr)95 inline BOOST::uint8_t const* Hes_Cpu::get_code( addr_t addr )
96 {
97 return cpu_state_.code_map [HES_CPU_PAGE( addr )] + HES_CPU_OFFSET( addr );
98 }
99
update_end_time(time_t end,time_t irq)100 inline void Hes_Cpu::update_end_time( time_t end, time_t irq )
101 {
102 if ( end > irq && !(r.flags & irq_inhibit_mask) )
103 end = irq;
104
105 cpu_state->time += cpu_state->base - end;
106 cpu_state->base = end;
107 }
108
set_irq_time(time_t t)109 inline void Hes_Cpu::set_irq_time( time_t t )
110 {
111 irq_time_ = t;
112 update_end_time( end_time_, t );
113 }
114
set_end_time(time_t t)115 inline void Hes_Cpu::set_end_time( time_t t )
116 {
117 end_time_ = t;
118 update_end_time( t, irq_time_ );
119 }
120
end_frame(time_t t)121 inline void Hes_Cpu::end_frame( time_t t )
122 {
123 assert( cpu_state == &cpu_state_ );
124 cpu_state_.base -= t;
125 if ( irq_time_ < future_time ) irq_time_ -= t;
126 if ( end_time_ < future_time ) end_time_ -= t;
127 }
128
set_mmr(int reg,int bank,void const * code)129 inline void Hes_Cpu::set_mmr( int reg, int bank, void const* code )
130 {
131 assert( (unsigned) reg <= page_count ); // allow page past end to be set
132 assert( (unsigned) bank < 0x100 );
133 mmr [reg] = bank;
134 byte const* p = STATIC_CAST(byte const*,code) - HES_CPU_OFFSET( reg << page_bits );
135 cpu_state->code_map [reg] = p;
136 cpu_state_.code_map [reg] = p;
137 }
138
139 #endif
140