1 files changed, 109 insertions, 0 deletions

diff --git a/lib/rbcodec/codecs/libgme/nes_cpu.h b/lib/rbcodec/codecs/libgme/nes_cpu.h
new file mode 100644
index 0000000000..e4538cd00c
--- /dev/null
+++ b/lib/rbcodec/codecs/libgme/nes_cpu.h
@@ -0,0 +1,109 @@
+// NES cpu emulator
+
+// Game_Music_Emu 0.6-pre
+#ifndef NES_CPU_H
+#define NES_CPU_H
+
+#include "blargg_common.h"
+#include "blargg_source.h"
+
+typedef int nes_time_t;
+typedef int addr_t;
+
+enum { page_bits = 11 };
+enum { page_size = 1 << page_bits };
+enum { page_count = 0x10000 >> page_bits };
+
+// Unmapped page should be filled with this
+enum { halt_opcode = 0x22 };
+
+enum { future_time = INT_MAX/2 + 1 };
+enum { irq_inhibit_mask = 0x04 };
+        
+// Can read this many bytes past end of a page
+enum { cpu_padding = 8 };
+
+struct registers_t {
+        uint16_t pc;
+        uint8_t a;
+        uint8_t x;
+        uint8_t y;
+        uint8_t flags;
+        uint8_t sp;
+};
+
+struct cpu_state_t {
+        uint8_t const* code_map [page_count + 1];
+        nes_time_t base;
+        int time;
+};
+
+struct Nes_Cpu {
+        // NES 6502 registers. NOT kept updated during emulation.
+        struct registers_t r;
+        nes_time_t irq_time;
+        nes_time_t end_time;
+        
+        struct cpu_state_t* cpu_state; // points to cpu_state_ or a local copy
+        struct cpu_state_t cpu_state_;
+};
+
+static inline void Cpu_init( struct Nes_Cpu* this )
+{
+        this->cpu_state = &this->cpu_state_;
+}
+
+// Clears registers and maps all pages to unmapped_page
+void Cpu_reset( struct Nes_Cpu* this, void const* unmapped_page );
+
+// Maps code memory (memory accessed via the program counter). Start and size
+// must be multiple of page_size. If mirror_size is non-zero, the first
+// mirror_size bytes are repeated over the range. mirror_size must be a
+// multiple of page_size.
+void Cpu_map_code( struct Nes_Cpu* this, addr_t start, int size, void const* code, int mirror_size );
+        
+// Time of beginning of next instruction to be executed
+static inline nes_time_t Cpu_time( struct Nes_Cpu* this ) { return this->cpu_state->time + this->cpu_state->base; }
+static inline void Cpu_set_time( struct Nes_Cpu* this, nes_time_t t ) { this->cpu_state->time = t - this->cpu_state->base; }
+static inline void Cpu_adjust_time( struct Nes_Cpu* this, int delta ) { this->cpu_state->time += delta; }
+        
+// Clocks past end (negative if before)
+static inline int Cpu_time_past_end( struct Nes_Cpu* this ) { return this->cpu_state->time; }
+                        
+#define NES_CPU_PAGE( addr ) ((unsigned) (addr) >> page_bits)
+
+#ifdef BLARGG_NONPORTABLE
+        #define NES_CPU_OFFSET( addr ) (addr)
+#else
+        #define NES_CPU_OFFSET( addr ) ((addr) & (page_size - 1))
+#endif
+
+// Accesses emulated memory as cpu does
+static inline uint8_t const* Cpu_get_code( struct Nes_Cpu* this, addr_t addr )
+{
+        return this->cpu_state_.code_map [NES_CPU_PAGE( addr )] + NES_CPU_OFFSET( addr );
+}
+
+static inline void Cpu_update_end_time( struct Nes_Cpu* this, nes_time_t end, nes_time_t irq )
+{
+        if ( end > irq && !(this->r.flags & irq_inhibit_mask) )
+                end = irq;
+        
+        this->cpu_state->time += this->cpu_state->base - end;
+        this->cpu_state->base = end;
+}
+
+// Time of next IRQ
+static inline void Cpu_set_irq_time( struct Nes_Cpu* this, nes_time_t t )
+{
+        this->irq_time = t;
+        Cpu_update_end_time( this, this->end_time, t );
+}
+
+static inline void Cpu_set_end_time( struct Nes_Cpu* this, nes_time_t t )
+{
+        this->end_time = t;
+        Cpu_update_end_time( this, t, this->irq_time );
+}
+
+#endif