segatools/platform/dipsw.c

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2023-07-13 22:41:23 +00:00
#include <windows.h>
#include <ntstatus.h>
#include <assert.h>
#include <string.h>
#include "platform/dipsw.h"
#include "platform/vfs.h"
#include "util/dprintf.h"
#include "util/str.h"
#include "util/crc.h"
#define DATA_SIZE 503
#define BLOCK_SIZE (sizeof(uint32_t) + 4 + 1 + DATA_SIZE)
#pragma pack(push, 1)
typedef struct
{
uint32_t checksum;
char padding_1[4];
uint8_t dip_switches;
char data[DATA_SIZE];
} DipSwitchBlock;
typedef struct
{
DipSwitchBlock dip_switch_block;
char *data;
} DipSwitches;
#pragma pack(pop)
static DipSwitches dip_switches;
static struct dipsw_config dipsw_config;
static struct vfs_config vfs_config;
static void dipsw_read_sysfile(const wchar_t *sys_file);
static void dipsw_save_sysfile(const wchar_t *sys_file);
HRESULT dipsw_init(const struct dipsw_config *cfg, const struct vfs_config *vfs_cfg)
{
HRESULT hr;
wchar_t sys_file_path[MAX_PATH];
assert(cfg != NULL);
assert(vfs_cfg != NULL);
if (!cfg->enable)
{
return S_FALSE;
}
memcpy(&dipsw_config, cfg, sizeof(*cfg));
sys_file_path[0] = L'\0';
// concatenate vfs_config.amfs with L"sysfile.dat"
wcsncpy(sys_file_path, vfs_cfg->amfs, MAX_PATH);
wcsncat(sys_file_path, L"\\sysfile.dat", MAX_PATH);
dipsw_read_sysfile(sys_file_path);
// now write the dipsw_config.dipsw to the dip_switch_block
dipsw_save_sysfile(sys_file_path);
return S_OK;
}
static void dipsw_read_sysfile(const wchar_t *sys_file)
{
FILE *f = _wfopen(sys_file, L"r");
if (f == NULL)
{
dprintf("First run detected, DipSw settings can only be applied AFTER the first run\n");
return;
}
fseek(f, 0, SEEK_END);
long file_size = ftell(f);
fseek(f, 0, SEEK_SET);
if (file_size != 0x6000)
{
dprintf("Invalid sysfile.dat file size\n");
fclose(f);
return;
}
dip_switches.data = malloc(file_size);
fread(dip_switches.data, 1, file_size, f);
fclose(f);
// memcpy(dip_switches.dip_switch_block, dip_switches.data + 0x2800, BLOCK_SIZE);
memcpy(&dip_switches.dip_switch_block, dip_switches.data + 0x2800, BLOCK_SIZE);
}
static void dipsw_save_sysfile(const wchar_t *sys_file)
{
uint8_t dipsw = 0;
// open the sysfile.dat for writing in bytes mode
FILE *f = _wfopen(sys_file, L"rb+");
if (f == NULL)
{
return;
}
// write the dipsw_config.dipsw to the dip_switch_block
for (int i = 0; i < 8; i++)
{
if (dipsw_config.dipsw[i])
{
// print which dipsw is enabled
dprintf("DipSw: DipSw%d=1 set\n", i + 1);
dipsw |= (1 << i);
}
}
dip_switches.dip_switch_block.dip_switches = dipsw;
// calculate the new checksum, skip the old crc32 value
// which is at the beginning of the block, thats's why the +4
// conver the struct to chars in order for the crc32 calculation to work
dip_switches.dip_switch_block.checksum = crc32(
(char *)&dip_switches.dip_switch_block + 4, BLOCK_SIZE - 4, 0);
// build the new dip switch block
char block[BLOCK_SIZE];
memcpy(block, (char *)&dip_switches.dip_switch_block, BLOCK_SIZE);
// replace the old block with the new one
memcpy(dip_switches.data + 0x2800, block, BLOCK_SIZE);
memcpy(dip_switches.data + 0x5800, block, BLOCK_SIZE);
// print the dip_switch_block in hex
/*
dprintf("DipSw Block: ");
for (size_t i = 0; i < BLOCK_SIZE; i++)
{
dprintf("%02X ", ((uint8_t *)&dip_switches.dip_switch_block)[i]);
}
dprintf("\n");
*/
fwrite(dip_switches.data, 1, 0x6000, f);
fclose(f);
}