Embedding ReWave

ReWave's portability

Embedding ReWave to your program is fairly easy. In fact, all you need to do is include ReWave's header(s) and link it to your build unit.

The embedded/host implementation:

/* host.cpp */

#include "vm.hpp"  /* ReWave's main header     */
#include <stdio.h> /* For reading the program  */

VM g_VM;           /* A global VM definition   */

#define RETURN(x) g_VM.memory[REG::AX] = x

/*
    This is the function where interrupts are handled.
    If it's not present the compilation will fail.

    "call" is the interrupt code.
*/
void interrupt(const uint32_t call) {
    enum {
        print,
        add
    };

    switch (call) {
        case print: /* BX = char_ptr */
            puts((const char*) &g_VM.program[g_VM.memory[REG::BX]]);
            break;

        case add: /* BX = x, CX = y, AX = return */
            RETURN(g_VM.memory[REG::BX] + g_VM.memory[REG::CX]);
            break;
    }
}

int main() {
    /* Feed the VM with the program code */
    uint32_t i = 0;

    FILE *f = fopen("file_goes_here.o", "r+");
    while (!feof(f))
    {
        g_VM.program[i++] = fgetc(f);
    }
    fclose(f);

    /* Restart the VM and cycle while it's running */
    g_VM.restart();
    while (g_VM.running) {
        g_VM.cycle();
    }
}

The ReWave program

; test.asm

__init:
    jmp main
    ret

print = 0x00
msg: #d "hello, world!", 0x00

main:
    ; void print(msg)
    mov BX, msg
    int print
    ext

Compiling the runtime with GCC and the source code with customasm:

g++ vm.cpp -c -o vm.o
g++ host.cpp vm.o -o host
customasm rulesdef.asm test.asm -f binary -o file_goes_here.o

And now you're ready to run your first ReWave program!

$ ./main
hello, world!
$