send button data to fifo

buttons.c

@@ -182,6 +182,7 @@ void ButtonISR(void) {
     ButtonReadJoystick();               // Convert joystick state to button presses. The result is in gButtons.
     uint32_t presses = ~old_buttons & gButtons;   // detect button presses (transitions from not pressed to pressed)
     presses |= ButtonAutoRepeat();      // autorepeat presses if a button is held long enough
+#ifdef DISPLAY_TIME
     static bool tic = false;
     static bool running = true;
     if (presses & 1) { // EK-TM4C1294XL button 1 pressed
@@ -190,11 +191,66 @@ void ButtonISR(void) {
     if (presses & 2) { // EK-TM4C1294XL button 2 pressed
         gTime = 0;
     }
-    if (presses & 4) { // boosterpack button 1 pressed
-        drawRequested = 1;
-    }
     if (running) {
         if (tic) gTime++; // increment time every other ISR call
         tic = !tic;
     }
+#endif // DISPLAY_TIME
+    Button buttons[9];
+    uint8_t length, i;
+    length = buttons_from_mask(buttons, presses);
+    for (i=0; i<length; i++) {
+        fifo_put(buttons[i]);
+    }
+}
+
+uint8_t buttons_from_mask(Button *array, uint32_t buttons) {
+    uint8_t i, len;
+    len = 0;
+
+    for(i=0; i<9; i++) {
+        if (buttons & 1) {
+            array[len++] = (Button) i;
+        }
+
+        buttons >>= 1;
+    }
+
+    return len;
+}
+
+volatile DataType button_fifo[FIFO_SIZE];  // FIFO storage array
+volatile int fifo_head = 0; // index of the first item in the FIFO
+volatile int fifo_tail = 0; // index one step past the last item
+
+// put data into the FIFO, skip if full
+// returns 1 on success, 0 if FIFO was full
+int fifo_put(DataType data)
+{
+    int new_tail = fifo_tail + 1;
+    if (new_tail >= FIFO_SIZE) new_tail = 0; // wrap around
+    if (fifo_head != new_tail) {    // if the FIFO is not full
+        button_fifo[fifo_tail] = data;     // store data into the FIFO
+        fifo_tail = new_tail;       // advance FIFO tail index
+        return 1;                   // success
+    }
+    return 0;   // full
+}
+
+// get data from the FIFO
+// returns 1 on success, 0 if FIFO was empty
+int fifo_get(DataType *data)
+{
+    if (fifo_head != fifo_tail) {   // if the FIFO is not empty
+        *data = button_fifo[fifo_head];    // read data from the FIFO
+        
+        if (fifo_head >= FIFO_SIZE-1) {
+            fifo_head = 0; // reset if past end
+        } else {
+            fifo_head++; // increment if within buffer
+        }
+
+        return 1;                   // success
+    }
+    return 0;   // empty
 }

buttons.h

@@ -52,4 +52,26 @@ void ButtonReadJoystick(void);
 // autorepeat button presses if a button is held long enough
 uint32_t ButtonAutoRepeat(void);
 
+typedef enum {
+    SW1 = 0,
+    SW2,
+    S1,
+    S2,
+    Select,
+    Right,
+    Left,
+    Up,
+    Down,
+} Button;
+
+// convert mask into array of buttons
+//
+// returns length
+uint8_t buttons_from_mask(Button *array, uint32_t buttons);
+
+#define FIFO_SIZE 11        // FIFO capacity is 1 item fewer
+typedef Button DataType;      // FIFO data type
+int fifo_put(DataType data);
+int fifo_get(DataType *data);
+
 #endif /* BUTTONS_H_ */

main.c

@@ -71,8 +71,11 @@ int main(void) {
     GrContextInit(&sContext, &g_sCrystalfontz128x128); // Initialize the grlib graphics context
     GrContextFontSet(&sContext, &g_sFontFixed6x8); // select font
 
+#ifdef DISPLAY_TIME
     uint32_t time;  // local copy of gTime
     char str[50];   // string buffer
+#endif // DISPLAY_TIME
+    
     // full-screen rectangle
     tRectangle rectFullScreen = {0, 0, GrContextDpyWidthGet(&sContext)-1, GrContextDpyHeightGet(&sContext)-1};