/*
 * vim:tabstop=4
 * vim:noexpandtab
 */
#include <system.h>
#include <syscall.h>


/*
 * System calls themselves
 */

/*
 * print something to the core terminal
 */
static int print(char * s) {
	kprintf(s);
	return 0;
}

/*
 * Exit the current task.
 * DOES NOT RETURN!
 */
static int exit(int retval) {
	/* Deschedule the current task */
	task_exit(retval);
	while (1) { };
	return retval;
}

/*
 * System Call Internals
 */
static void syscall_handler(struct regs * r);
static uintptr_t syscalls[] = {
	/* System Call Table */
	(uintptr_t)&exit,
	(uintptr_t)&print
};
uint32_t num_syscalls = 2;

void
syscalls_install() {
	isrs_install_handler(0x7F, &syscall_handler);
}

void
syscall_handler(
		struct regs * r
		) {
	if (r->eax >= num_syscalls) {
		return;
	}
	uintptr_t location = syscalls[r->eax];

	uint32_t ret;
	__asm__ __volatile__ (
			"push %1\n"
			"push %2\n"
			"push %3\n"
			"push %4\n"
			"push %5\n"
			"call *%6\n"
			"pop %%ebx\n"
			"pop %%ebx\n"
			"pop %%ebx\n"
			"pop %%ebx\n"
			"pop %%ebx\n"
			: "=a" (ret) : "r" (r->edi), "r" (r->esi), "r" (r->edx), "r" (r->ecx), "r" (r->ebx), "r" (location));
	r->eax = ret;
}