bah, j'ai trouvé une solution:

switch ((*pEnvironment)->toki.sprite.direction)
{
case DIRECTION_LEFT:
	if ((*pEnvironment)->toki.startJump.x-(*pEnvironment)->toki.sprite.location.x < TILE_WIDTH)
		(*pEnvironment)->toki.sprite.location.x-=(*pEnvironment)->toki.speed.cx;
	else
	{
		// jump over
		(*pEnvironment)->toki.nJumping=0;

		// check if fall...
		if (!Fall(pEnvironment))
			Land(pEnvironment);
	}

	break;

case DIRECTION_RIGHT:
	if ((*pEnvironment)->toki.sprite.location.x-(*pEnvironment)->toki.startJump.x < TILE_WIDTH)
		(*pEnvironment)->toki.sprite.location.x+=(*pEnvironment)->toki.speed.cx;
	else
	{
		// jump over
		(*pEnvironment)->toki.nJumping=0;

		// check if fall...
		if (!Fall(pEnvironment))
			Land(pEnvironment);
	}
	break;

default:
	break;
}

et là, ça marche bien