Syscalls from BrainFuck
Because why not
The interpreter has various syscalls to access the hardware of the system, because BrainFuck doesn’t have the functionality for this.
How a syscall works is, basically:
The BrainFuck code uses the out . instruction to output a string of chars with this format to do a system call:
[SYSTEMCALL]<params>
4 chars for the syscall’s name, and then the parameters.
For example, to print “Hello world”, without any line breaks:
PRNTHello World\0
Not all syscalls end with null chars, only the ones that use strings do this. (SCPX, setCursorPosX, for example, receives a 16-bit int, 2 bytes in big endian, for its parameter, without any null chars)
To receive the output from a syscall, we repeatedly call the in , instruction until we receive all the bytes we want. For example, to get the output from the READ syscall, which returns a null terminated string:
void print(int[] s) {
int i = 0;
while(s[i] != 0) {
write_char(s[i]);
i = i + 1;
}
}
void read(int[] s, int size) {
int r[] = "READ";
print(r);
int i = 0;
int rchar = -1;
while(rchar != 0 || i < size) {
rchar = read_char();
s[i] = rchar;
i = i + 1;
}
}
int input[40];
read(input, 40);