64 lines
3.5 KiB
C
64 lines
3.5 KiB
C
// https://discord.com/channels/642647820683444236/646765703143227394/836663602718048297
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// 28-04-2021 - @nicolasnoble:
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//
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// step 0 : have a protocol that can handle open / close / seek / read / write
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//
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// 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)
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//
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// step 1.5: implement the pcopen / pcclose / pcread / pcwrite / pcseek functions, which are basically the same model as my syscalls.h file
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//
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// 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
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// this step requires understanding the ReturnFromException mechanism basically which, to be fair, is sort of understandable from this one file:
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// https://github.com/grumpycoders/pcsx-redux/blob/main/src/mips/openbios/handlers/syscall.c
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// you can see the syscall_unresolvedException() call at the bottom , this just needs to follow the same pattern
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// and break down the caller, modify the current thread's registers, and return to the caller
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// at this point, we have a working basic pcdrv feature, using pcopen / pcclose / pcread / pcwrite / pcseek
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//
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// 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);
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// (and thus support things like CSOTN technically)
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//
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// https://discord.com/channels/642647820683444236/646765703143227394/837416216640618558
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// So like we'd have, say,
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// 00 01 00 03 58 58 58 01 xx for pcdrv' file open to open the file name "XXX" and attribute 1
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// (escape) (pcdrv command) (pcdrv open) (filename with length as prefix) (attributes) (checksum)
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#pragma once
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#include <sys/types.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <stdio.h>
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//~ #include <libsio.h>
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#include <string.h>
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#define BUFFER_LEN 8
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#define ESCAPE 0x00 // Hypothetical Escape char for unirom
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#define PROTOCOL 0x01
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//pcdrv commands
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#define OPEN 0x00
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#define CLOSE 0x01
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#define SEEK 0x02
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#define READ 0x03
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#define WRITE 0x04
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#define CREATE 0x05
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#define LOAD 0x06
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#define INIT 0x07
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// flags parameters
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#define O_RDONLY 0x00
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#define O_WRONLY 0x01
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#define O_RDWR 0x02
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#define CHECKSUM_LEN 10
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//~ static char sio_read();
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int waitForSIODone( const char * answer, volatile char * bufferAddress);
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static inline uint32_t djbHash( const char* str, unsigned n );
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static inline uint32_t djbProcess(uint32_t hash, const char str[], unsigned n);
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//~ uint32_t charsToU32 ( char * byte );
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//~ u_char U32ToChars( u_int memoryAddress, u_int byteNbr);
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//~ void sendU32(uint32_t data);
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//~ void sendRU32(uint32_t data);
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u_short PCload( u_long * loadAddress, volatile u_char * bufferAddress, u_char * overlayFileID );
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int PCinit( volatile u_char * bufferAddress );
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int PCclose( int fileDesc, volatile u_char * bufferAddress );
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int PCopen( const char * filename, u_char mode, volatile u_char * bufferAddress );
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int PCcreate( const char * filename, u_char mode, volatile u_char * bufferAddress );
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int PCseek( int fd, int curPos, int offset, int accessMode, volatile u_char * bufferAddress );
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int PCread( int fd, int pos, int len, volatile char * dataBuffer, volatile char * bufferAddress );
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int PCwrite( int fd, int pos, int len, volatile u_char * dataBuffer, volatile u_char * bufferAddress );
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