/*

Tutorial 5 - gcd, with tail call optimization

Builds and compiles the following function:

unsigned int gcd(unsigned int x, unsigned int y)
{
    if(x == y)
    {
        return x;
    }
    else if(x < y)
    {
        return gcd(x, y - x);
    }
    else
    {
        return gcd(x - y, y);
    }
}

*/

#include <stdio.h>
#include <jit/jit.h>

int main(int argc, char **argv)
{
	jit_context_t context;
	jit_type_t params[2];
	jit_type_t signature;
	jit_function_t function;
	jit_value_t x, y;
	jit_value_t temp1, temp2;
	jit_value_t temp_args[2];
	jit_label_t label1 = jit_label_undefined;
	jit_label_t label2 = jit_label_undefined;
	jit_uint arg1, arg2;
	void *args[2];
	jit_uint result;

	/* Create a context to hold the JIT's primary state */
	context = jit_context_create();

	/* Lock the context while we build and compile the function */
	jit_context_build_start(context);

	/* Build the function signature */
	params[0] = jit_type_uint;
	params[1] = jit_type_uint;
	signature = jit_type_create_signature
		(jit_abi_cdecl, jit_type_uint, params, 2, 1);

	/* Create the function object */
	function = jit_function_create(context, signature);
	jit_type_free(signature);

	/* Check the condition "if(x == y)" */
	x = jit_value_get_param(function, 0);
	y = jit_value_get_param(function, 1);
	temp1 = jit_insn_eq(function, x, y);
	jit_insn_branch_if_not(function, temp1, &label1);

	/* Implement "return x" */
	jit_insn_return(function, x);

	/* Set "label1" at this position */
	jit_insn_label(function, &label1);

	/* Check the condition "if(x < y)" */
	temp2 = jit_insn_lt(function, x, y);
	jit_insn_branch_if_not(function, temp2, &label2);

	/* Implement "return gcd(x, y - x)" */
	temp_args[0] = x;
	temp_args[1] = jit_insn_sub(function, y, x);
	jit_insn_call(function, "gcd", function, 0, temp_args, 2, JIT_CALL_TAIL);

	/* Set "label2" at this position */
	jit_insn_label(function, &label2);

	/* Implement "return gcd(x - y, y)" */
	temp_args[0] = jit_insn_sub(function, x, y);
	temp_args[1] = y;
	jit_insn_call(function, "gcd", function, 0, temp_args, 2, JIT_CALL_TAIL);

	/* Compile the function */
	jit_function_compile(function);

	/* Unlock the context */
	jit_context_build_end(context);

	/* Execute the function and print the result */
	arg1 = 27;
	arg2 = 14;
	args[0] = &arg1;
	args[1] = &arg2;
	jit_function_apply(function, args, &result);
	printf("gcd(27, 14) = %u\n", (unsigned int)result);

	/* Clean up */
	jit_context_destroy(context);

	/* Finished */
	return 0;
}