file.h

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#ifndef FILE_H
#define FILE_H
 
#include "types.h"
 
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wreturn-type"
#pragma GCC diagnostic ignored "-Wunused-parameter"
 
//https://cplusplus.com/reference/cstdio/FILE/
 
typedef struct {
    Byte id;
    Word size;
} FILE;
 
FILE *open(int filename, int mode) {
    //https://pubs.opengroup.org/onlinepubs/9699919799/functions/fopen.html
    static FILE file;
    short val;
    asm ("int 0x21":"=a"(val):"a"(0x100), "b"(filename));
    if(val < 0)
        return NULL;
    file.id = (Byte)val;
    file.size = (val >> 8) * 512;//sys_open returns size in Sectors
    return &file;
}
 
int read ( int buf, size_t size, FILE * stream ) {
    asm("int 0x21"::"a"(0x0200), "b"(stream->id), "c"(buf), "d"(size));
}
 
 
int write ( int buf, size_t size, FILE * stream ) {
    asm("int 0x21"::"a"(0x0300), "b"(stream->id), "c"(buf), "d"(size));
}
 
int create(const int filename, size_t size) {
    asm("int 0x21"::"a"(0x0400), "b"(filename), "c"(size));
}
 
int remove(const int filename) {
    asm("int 0x21"::"a"(0x0500), "b"(filename));
}
 
#pragma GCC diagnostic pop
#endif