apps/codecs/libgme/nes_cpu.c

   1 // Game_Music_Emu 0.6-pre. http://www.slack.net/~ant/
   2
   3 #include "nes_cpu.h"
   4
   5 #include "blargg_endian.h"
   6
   7 /* Copyright (C) 2003-2008 Shay Green. This module is free software; you
   8 can redistribute it and/or modify it under the terms of the GNU Lesser
   9 General Public License as published by the Free Software Foundation; either
  10 version 2.1 of the License, or (at your option) any later version. This
  11 module is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
  14 details. You should have received a copy of the GNU Lesser General Public
  15 License along with this module; if not, write to the Free Software Foundation,
  16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
  17
  18 #include "blargg_source.h"
  19
  20 inline void set_code_page( struct Nes_Cpu* this, int i, void const* p )
  21 {
  22         byte const* p2 = STATIC_CAST(byte const*,p) - NES_CPU_OFFSET( i * page_size );
  23         this->cpu_state->code_map [i] = p2;
  24         this->cpu_state_.code_map [i] = p2;
  25 }
  26
  27 void Cpu_map_code( struct Nes_Cpu* this, addr_t start, int size, void const* data, int mirror_size )
  28 {
  29         // address range must begin and end on page boundaries
  30         require( start % page_size == 0 );
  31         require( size  % page_size == 0 );
  32         require( start + size <= 0x10000 );
  33         require( mirror_size % page_size == 0 );
  34
  35         int offset;
  36         for ( offset = 0; offset < size; offset += page_size )
  37                 set_code_page( this, NES_CPU_PAGE( start + offset ),
  38                                 STATIC_CAST(char const*,data) + (offset & ((unsigned) mirror_size - 1)) );
  39 }
  40
  41 void Cpu_reset( struct Nes_Cpu* this, void const* unmapped_page )
  42 {
  43         check( this->cpu_state == &this->cpu_state_ );
  44         this->cpu_state = &this->cpu_state_;
  45
  46         this->r.flags = irq_inhibit_mask;
  47         this->r.sp = 0xFF;
  48         this->r.pc = 0;
  49         this->r.a  = 0;
  50         this->r.x  = 0;
  51         this->r.y  = 0;
  52
  53         this->cpu_state_.time = 0;
  54         this->cpu_state_.base = 0;
  55         this->irq_time = future_time;
  56         this->end_time = future_time;
  57
  58         set_code_page( this, page_count, unmapped_page );
  59         Cpu_map_code( this, 0, 0x10000, unmapped_page, page_size );
  60
  61         blargg_verify_byte_order();
  62 }