Input buffering system, implemented for jumping.

include/player.h

@@ -17,7 +17,7 @@ typedef struct Player {
 #include "input.h"
 
 void player_move(Player *player, const Level *level);
-void player_step(Player *player, Input *input, const Level *level);
+void player_step(Player *player, Input *input, const Level *level, uint step);
 void player_draw(Player *player, Camera *camera);
 void player_draw_debug(Player *player, uint step, const Level *level, uint layer_id);
 

src/input.c

@@ -60,7 +60,7 @@ bool input_is_pressed(Input *input, uint8_t key) {
 }
 
 uint input_last_press(Input *input, uint8_t key, uint step) {
-	return input->last_press[key] - step;
+	return step - input->last_press[key];
 }
 
 bool input_is_down(Input *input, uint8_t key) {

src/main.c

@@ -85,7 +85,7 @@ int callback(volatile void *arg) {
 void step_event(Player *player, const Level *level, Camera *camera, Input *input, uint step) {
 	//getkey();
 	input_step(input, step);
-	player_step(player, input, level);
+	player_step(player, input, level, step);
 	level_step(level);
 	camera_step(camera);
 }

src/player.c

@@ -15,6 +15,7 @@
 #define GRAVITY PXS
 #define JUMP_SPD (-128 * PXS)
 #define GRACE_UNITS (int)(UPS / 5)
+#define EARLY_UNITS (int)(UPS / 5)
 #define SGN(x) ((x > 0) ? (1) : ((x < 0) ? (-1) : (0)))
 #define PLAYER_COLLIDE(pos) player_collide(player, pos, level, level->solid_layer)
 
@@ -54,7 +55,7 @@ void player_move(Player *player, const Level *level) {
 	vec_cpy(&player->pos, destination);
 }
 
-void player_step(Player *player, Input *input, const Level *level) {
+void player_step(Player *player, Input *input, const Level *level, uint step) {
 	/* Get directionnal input and assign it to move.x/move.y:
 	 * i.e., if the player hold left and down move will have
 	 * move.x = -1 and move.y = 1. */
@@ -63,7 +64,7 @@ void player_step(Player *player, Input *input, const Level *level) {
 		(INPUT_DOWN(K_DOWN) - INPUT_DOWN(K_UP))
 	};
 	/* other keys */
-	bool kp_jump = INPUT_PRESSED(K_JUMP);
+	bool k_jump = INPUT_DOWN(K_JUMP);
 	int xacc = move.x * ACCELERATION; /* calculate horizontal acceleration */
 	player->spd.x *= FRICTION; /* apply horizontal friction */
 	player->spd.x += xacc; /* apply horizontal acceleration */
@@ -72,7 +73,7 @@ void player_step(Player *player, Input *input, const Level *level) {
 	 * time after leaving a platform. */
 	if (player->grace) {
 		player->grace -= 1;
-		if (kp_jump) {
+		if (k_jump && (INPUT_LAST_PRESS(K_JUMP) <= EARLY_UNITS)) {
 			/* If the player try to jump and can, prevent
 			 * them to do it again and assign them the
 			 * corresponding y speed. */