1 files changed, 80 insertions, 0 deletions

diff --git a/lib/rbcodec/codecs/libgme/gb_cpu.h b/lib/rbcodec/codecs/libgme/gb_cpu.h
new file mode 100644
index 0000000000..37b22141d7
--- /dev/null
+++ b/lib/rbcodec/codecs/libgme/gb_cpu.h
@@ -0,0 +1,80 @@
+// Nintendo Game Boy CPU emulator
+
+// Game_Music_Emu 0.6-pre
+#ifndef GB_CPU_H
+#define GB_CPU_H
+
+#include "blargg_common.h"
+#include "blargg_source.h"
+
+typedef int addr_t;
+
+// Emulator reads this many bytes past end of a page
+enum { cpu_padding = 8 };
+enum { mem_size = 0x10000 };
+enum { page_bits = 13 };
+enum { page_size = 1 << page_bits };
+enum { page_count = mem_size >> page_bits };
+
+// Game Boy Z-80 registers. NOT kept updated during emulation.
+struct core_regs_t {
+        uint16_t bc, de, hl, fa;
+};
+        
+struct registers_t {
+        int pc; // more than 16 bits to allow overflow detection
+        uint16_t sp;
+
+        struct core_regs_t rp;
+};
+
+struct cpu_state_t {
+        byte* code_map [page_count + 1];
+        int time;
+};
+
+struct Gb_Cpu { 
+        // Base address for RST vectors, to simplify GBS player (normally 0)
+        addr_t rst_base;
+        
+        struct registers_t r;
+        struct cpu_state_t* cpu_state; // points to state_ or a local copy within run()
+        struct cpu_state_t cpu_state_;
+};
+
+// Initializes Gb cpu
+static inline void Cpu_init( struct Gb_Cpu* this )
+{
+        this->rst_base = 0;
+        this->cpu_state = &this->cpu_state_;
+}
+
+// Clears registers and map all pages to unmapped
+void Cpu_reset( struct Gb_Cpu* this, void* unmapped );
+        
+// Maps code memory (memory accessed via the program counter). Start and size
+// must be multiple of page_size.
+void Cpu_map_code( struct Gb_Cpu* this, addr_t start, int size, void* code );
+                        
+// Current time.
+static inline int Cpu_time( struct Gb_Cpu* this ) { return this->cpu_state->time; }
+        
+// Changes time. Must not be called during emulation.
+// Should be negative, because emulation stops once it becomes >= 0.
+static inline void Cpu_set_time( struct Gb_Cpu* this, int t ) { this->cpu_state->time = t; }
+
+#define GB_CPU_PAGE( addr ) ((unsigned) (addr) >> page_bits)
+
+#ifdef BLARGG_NONPORTABLE
+        #define GB_CPU_OFFSET( addr ) (addr)
+#else
+        #define GB_CPU_OFFSET( addr ) ((addr) & (page_size - 1))
+#endif
+
+// Accesses emulated memory as CPU does
+static inline uint8_t* Cpu_get_code( struct Gb_Cpu* this, addr_t addr )
+{
+        return this->cpu_state_.code_map [GB_CPU_PAGE( addr )] + GB_CPU_OFFSET( addr );
+}
+
+#endif