155 lines
4.5 KiB
C
155 lines
4.5 KiB
C
#include "file.h"
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void init_rom_elements( rom_image *rom )
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{
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rom->console = UNKNOWN;
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rom->mapper = UNKNOWN;
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rom->submap = UNKNOWN;
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rom->mapvariant = UNKNOWN;
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rom->prg_size = UNKNOWN;
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rom->chr_size = UNKNOWN;
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rom->ram_size = UNKNOWN;
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rom->battery = UNKNOWN;
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rom->mirroring = UNKNOWN;
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rom->fileptr = NULL;
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}
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//Need to pass in pointer to a filepointer to properly pass by reference
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//the OS/stdio creates a FILE struct and returns the address of that struct
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//so when this function opens a file it's setting the value of a pointer
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//for the calling function. To set a pointer we must have a pointer to that pointer..
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//int open_file( FILE **fptr, char *filename )
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int open_rom( rom_image *rom, char *filename )
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{
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//first open file
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//*fptr = fopen( filename, "rb");
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rom->fileptr = fopen( filename, "rb");
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//returns file ptr on success, NULL on fail
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//check( *fptr, "Unable to open file: %s in read binary mode", filename);
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check( rom->fileptr, "Unable to open file: %s in read binary mode", filename);
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return SUCCESS;
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error:
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return -1;
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}
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int close_rom( rom_image *rom )
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{
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debug("flushing");
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fflush(rom->fileptr);
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debug("closing");
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return fclose( rom->fileptr );
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}
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int detect_file( rom_image *rom )
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{
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int rv = 0;
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uint8_t header[SIZE_NES_HEADER];
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//size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
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rv = fread( header, sizeof(header[0]), (sizeof(header)/sizeof(header[0])), rom->fileptr);
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check( rv == sizeof(header), "Unable to read NES header");
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//0-3: Constant $4E $45 $53 $1A ("NES" followed by MS-DOS end-of-file)
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if ( (header[0]=='N') && (header[1]=='E') && (header[2]=='S') && (header[3]==0x1A) ) {
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debug("detected ines header");
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rom->console = NES_CART;
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} else {
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debug("only ines files currently accepted as input");
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goto error;
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}
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//4: Size of PRG ROM in 16 KB units
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rom->prg_size = header[4] * SIZE_PRG_BANK;
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debug("PRG ROM size= %d", rom->prg_size);
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//5: Size of CHR ROM in 8 KB units (Value 0 means the board uses CHR RAM)
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rom->chr_size = header[5] * SIZE_CHR_BANK;
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debug("CHR ROM size= %d", rom->chr_size);
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//6: Flags 6
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// 76543210
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// ||||||||
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// ||||+||+- 0xx0: vertical arrangement/horizontal mirroring (CIRAM A10 = PPU A11)
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// |||| || 0xx1: horizontal arrangement/vertical mirroring (CIRAM A10 = PPU A10)
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// |||| || 1xxx: four-screen VRAM
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// |||| |+-- 1: Cartridge contains battery-backed PRG RAM ($6000-7FFF) or other persistent memory
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// |||| +--- 1: 512-byte trainer at $7000-$71FF (stored before PRG data)
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// ++++----- Lower nybble of mapper number
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rom->mapper = (header[6]>>4);
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rom->mapper |= (header[7] & 0xF0);
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debug("mapper #%d", rom->mapper);
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rom->mirroring = header[6] & 0x09; //0b0000 1001
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debug("mirroring:%x", rom->mirroring);
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//7: Flags 7
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// 76543210
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// ||||||||
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// |||||||+- VS Unisystem
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// ||||||+-- PlayChoice-10 (8KB of Hint Screen data stored after CHR data)
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// ||||++--- If equal to 2, flags 8-15 are in NES 2.0 format
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// ++++----- Upper nybble of mapper number
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//8: Size of PRG RAM in 8 KB units (Value 0 infers 8 KB for compatibility; see PRG RAM circuit)
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//9: Flags 9
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//10: Flags 10 (unofficial)
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//11-15: Zero filled
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return SUCCESS;
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error:
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return -1;
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}
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int create_file( rom_image *rom, char *filename )
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{
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//TODO check if file already exists, if so prompt if user would like to overwrite
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rom->fileptr = fopen( filename, "wb+");
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check( rom->fileptr, "Unable to create file: %s in read/write binary mode", filename);
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return SUCCESS;
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error:
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return -1;
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}
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/* Desc:Append data to rom file
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* Pre: rom file created and opened
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* Post:data of length appended to file
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* file still open
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* Rtn: SUCCESS if no errors
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*/
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int append_to_file( rom_image *rom, uint8_t *data, int length )
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{
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int rv = 0;
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//size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
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rv = fwrite( data, sizeof(data[0]), length, rom->fileptr );
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check( (rv == length), "Error appending to file, %dB out written when trying to write %d", rv, length);
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return SUCCESS;
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error:
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return -1;
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}
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/* Desc:Read data from file
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* Pre: file opened and current position set to desired location
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* Post:data filled with length amount of data from file
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* file still open
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* Rtn: SUCCESS if no errors
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*/
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int read_from_file( rom_image *rom, uint8_t *data, int length )
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{
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int rv = 0;
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//size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
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rv = fread( data, sizeof(data[0]), length, rom->fileptr );
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check( (rv == length), "Error reading from file, %dB read when trying to read %d", rv, length);
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return SUCCESS;
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error:
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return -1;
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}
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