62 lines
2.6 KiB
C
62 lines
2.6 KiB
C
// https://discord.com/channels/642647820683444236/646765703143227394/836663602718048297
|
|
// 28-04-2021 - @nicolasnoble:
|
|
//
|
|
// step 0 : have a protocol that can handle open / close / seek / read / write
|
|
//
|
|
// step 1 : have an unhandled exception handler installed in the kernel to capture the pcdrv functions; that sounds scary, but it's extremely straightforward (I think @sickle currently has one for his debugger)
|
|
//
|
|
// step 1.5: implement the pcopen / pcclose / pcread / pcwrite / pcseek functions, which are basically the same model as my syscalls.h file
|
|
//
|
|
// step 2 : implement the unhandler exception handler in a way that properly redirects the calls to the step 0 protocol, and returns gracefully to the caller when done - that can be a bit tricky, but it's totally doable
|
|
// this step requires understanding the ReturnFromException mechanism basically which, to be fair, is sort of understandable from this one file:
|
|
// https://github.com/grumpycoders/pcsx-redux/blob/main/src/mips/openbios/handlers/syscall.c
|
|
// you can see the syscall_unresolvedException() call at the bottom , this just needs to follow the same pattern
|
|
// and break down the caller, modify the current thread's registers, and return to the caller
|
|
// at this point, we have a working basic pcdrv feature, using pcopen / pcclose / pcread / pcwrite / pcseek
|
|
//
|
|
// step 3 : add a kernel driver for "pcdrv:" that just piggy backs on pc* functions so that people can simply do a int file = open("pcdrv:blah.txt", O_RDONLY);
|
|
// (and thus support things like CSOTN technically)
|
|
//
|
|
// https://discord.com/channels/642647820683444236/646765703143227394/837416216640618558
|
|
// So like we'd have, say,
|
|
// 00 01 00 03 58 58 58 01 xx for pcdrv' file open to open the file name "XXX" and attribute 1
|
|
|
|
// (escape) (pcdrv command) (pcdrv open) (filename with length as prefix) (attributes) (checksum)
|
|
|
|
|
|
#pragma once
|
|
|
|
#include <sys/types.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
|
|
|
|
//pcdrv commands
|
|
|
|
#define OPEN 0
|
|
#define CLOSE 1
|
|
#define SEEK 2
|
|
#define READ 3
|
|
#define WRITE 4
|
|
#define CREATE 5
|
|
#define LOAD 6
|
|
|
|
static inline uint32_t djbHash( const char* str, unsigned n );
|
|
|
|
static inline uint32_t djbProcess(uint32_t hash, const char str[], unsigned n);
|
|
|
|
int waitForSIODone( int * flag );
|
|
|
|
void PCload( u_long * loadAddress, volatile u_char * flagAddress, u_char overlayFileID );
|
|
|
|
int PCopen( const char * filename, int attributes );
|
|
|
|
int PCcreate(const char * filename, int attributes );
|
|
|
|
int PCclose( int fd );
|
|
|
|
int PCseek( int fd, int offset, int accessMode );
|
|
|
|
int PCread( int fd, int len, char * buffer );
|
|
|