bslathi19/super6502
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Replace bios with bootloader, don't use bootsector

Browse Source 
Instead of using the bootsector to load a bootloader, just put the
bootloader in the ROM and call it a day. It looks for a file on the SD
card in the root directory named `kernel.bin` and loads it into memory.

This is not a perfect solution, as the kernel will grow larger and the
kernel load address will have to change. At this point I could add back
the bootloader, but that is for later.

Also the bootloader is just a copy of the kernel, so that can be trimmed
down a lot.
This commit is contained in:
Byron Lathi
2022-04-19 10:34:19 -05:00
parent f664d59497
commit f3c7ac9696
42 changed files with 1295 additions and 232 deletions
Download Patch File Download Diff File Expand all files Collapse all files

61
sw/bootloader/exec.c Normal file
View File

@@ -0,0 +1,61 @@
#include <stdint.h>
#include <conio.h>
#include <string.h>
#include "filesystem/fat.h"
#include "filesystem/o65.h"
void exec(char* filename) {
o65_header_t* header;
o65_opt_t* o65_opt;
uint8_t* seg_ptr;
uint8_t* code_base;
uint8_t* data_base;
uint16_t code_len;
uint16_t data_len;
uint8_t (*exec)(void);
uint8_t ret;
fat_read(filename, fat_buf);
header = (o65_header_t*)fat_buf;
if (header->c64_marker == O65_NON_C64 &&
header->magic[0] == O65_MAGIC_0 &&
header->magic[1] == O65_MAGIC_1 &&
header->magic[2] == O65_MAGIC_2) {
code_base = (uint8_t*)header->tbase;
data_base = (uint8_t*)header->dbase;
code_len = header->tlen;
data_len = header->dlen;
o65_opt = (o65_opt_t*)(fat_buf + sizeof(o65_header_t));
while (o65_opt->olen)
{
o65_print_option(o65_opt);
o65_opt = (o65_opt_t*)((uint8_t*)o65_opt + o65_opt->olen);
}
seg_ptr = (uint8_t*)o65_opt + 1;
memcpy((uint8_t*)code_base, seg_ptr, code_len);
seg_ptr+=code_len;
memcpy((uint8_t*)data_base, seg_ptr, data_len);
exec = (uint8_t (*)(void))code_base;
ret = 0;
ret = (*exec)();
cprintf("ret: %x\n", ret);
}
}