cd.c

/*
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  This file is part of Etripator,
  copyright (c) 2009--2024 Vincent Cruz.
 
  Etripator is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
 
  Etripator is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
  along with Etripator.  If not, see <http://www.gnu.org/licenses/>.

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*/
#include "cd.h"
#include "message.h"

/// Adds CD RAM to memory map.
bool cd_memory_map(MemoryMap *map) {
    int i;
    bool ret = false;
    // Allocate CD RAM 
    if(!memory_create(&map->memory[PCE_MEMORY_CD_RAM], PCE_CD_RAM_BANK_COUNT * PCE_BANK_SIZE)) {
        ERROR_MSG("Failed to allocate cd memory!");
    // Allocate System Card RAM
    } else if (!memory_create(&map->memory[PCE_MEMORY_SYSCARD_RAM], PCE_SYSCARD_RAM_BANK_COUNT * PCE_BANK_SIZE)) {
        ERROR_MSG("Failed to allocate system card memory!");
    } else {
        // CD RAM is mapped to pages 0x80-0x88 (included).
        for (i = 0; i <= PCE_CD_RAM_BANK_COUNT; i++) {
            map->page[PCE_CD_RAM_FIRST_PAGE + i].id = PCE_MEMORY_CD_RAM;
            map->page[PCE_CD_RAM_FIRST_PAGE + i].bank = i;
        }
        // System Card RAM is mapped to pages 0x68-0x86.
        for (i = 0; i < PCE_SYSCARD_RAM_BANK_COUNT; i++) {
            map->page[PCE_SYSCARD_RAM_FIRST_PAGE + i].id = PCE_MEMORY_SYSCARD_RAM;
            map->page[PCE_SYSCARD_RAM_FIRST_PAGE + i].bank = i;
        }
        ret = true;
    }

    if(ret == false) {
        memory_map_destroy(map);
    }
    return ret;
}

/// Load CDROM data from file.
bool cd_load(const char* filename, size_t start, size_t len, size_t sector_size, uint8_t page, size_t offset, MemoryMap* map) {
    bool ret = false;
    FILE *in = fopen(filename, "rb");
    if(in == NULL) {
        ERROR_MSG("Unable to open %s : %s", filename, strerror(errno));
    } else {
        size_t remaining = len;
        size_t physical = (offset & 0x1FFFU) | (page << 0x0D);
        for(ret=true; ret && remaining; ) {
            size_t count = 2048 - (start % 2048);
            if(count > remaining) {
                count = remaining;
            }

            size_t sector_id = start / 2048;
            size_t sector_offset = start % 2048;
            
            size_t file_offset = (sector_id * sector_size) + sector_offset;

            size_t current_page = physical >> 0x0D;
            size_t current_addr = physical & 0x1FFF;

            size_t bank_offset = current_addr + (map->page[current_page].bank * PCE_BANK_SIZE);

            // [todo] test that map->page[current_page].id != PCE_MEMORY_NONE

            ret = false;
            if(fseek(in, (long int)file_offset, SEEK_SET) < 0) {
                ERROR_MSG("Offset out of bound : %s", strerror(errno));
            } else if(fread(map->memory[map->page[current_page].id].data+bank_offset, 1, count, in) != count) {
                ERROR_MSG("Failed to read %d bytes : %s", count, strerror(errno));
            } else {
                ret = true;
            }
            start += count;
            physical += count;
            remaining -= count;
        }
  
    }    
    if(in) {
        fclose(in);
    }
    return ret;
}