[ion] better ion_getchar

ion/include/ion/keyboard.h

@@ -44,14 +44,13 @@ typedef enum {
   ION_KEY_G_2,
   ION_KEY_G_3,
   ION_KEY_G_4,
-  ION_KEY_G_5,
-
-  ION_KEY_LAST
+  ION_KEY_G_5
 } ion_key_t;
 
 #define ION_NUMBER_OF_KEYS 35
 
-bool ion_key_state(ion_key_t key);
+// FIXME: Which state is "true"?
+bool ion_key_down(ion_key_t key);
 
 // This is our keymap
 char ion_getchar();

ion/platform/device/keyboard.c

@@ -50,22 +50,27 @@ static inline uint8_t column_for_key(ion_key_t key) {
   return key%5;
 }
 
-bool ion_key_state(ion_key_t key) {
+bool ion_key_down(ion_key_t key) {
   /* Drive the corresponding row low, and let all the others float.
-   * Note: In open-drain mode, a 0 in the register drives low, and a 1 let the
+   * Note: In open-drain mode, a 0 in the register drives low, and a 1 lets the
    * pin in Hi-Z (floating). */
-  GPIO_ODR(GPIOA) = ~(1 << (column_for_key(key)+ROW_PIN_START));
+  uint32_t output_mask = (((uint32_t)1 << (ROW_PIN_END-ROW_PIN_START+1)) - 1) << ROW_PIN_START;
+  uint32_t previous_odr = GPIO_ODR(GPIOA);
+  uint32_t new_odr = ~((uint32_t)1 << (row_for_key(key)+ROW_PIN_START)) & output_mask;
 
-  // Wait a little...
-  for (int i=0;i<10000;i++) {
+  if (new_odr != previous_odr) {
+    GPIO_ODR(GPIOA) = new_odr;
+    // We changed the outputs, give the hardware some time to react to this change
+    // FIXME: Real delay!
+    for (int i=0;i<1000; i++) {
+    }
   }
 
   // Read the input of the proper column
-  uint32_t input = (GPIO_IDR(GPIOA) & (1 << (row_for_key(key)+COLUMN_PIN_START)));
+  uint32_t input = (GPIO_IDR(GPIOA) & (1 << (column_for_key(key)+COLUMN_PIN_START)));
 
-  // The key is pressed if the input is brought low by the output. In other
-  // words, we want to return "true" (1) if the input is low (0).
-  // Return the logical opposite of what we've just read
+  /* The key is down if the input is brought low by the output. In other words,
+   * we want to return "true" (1) if the input is low (0). */
   return (input == 0);
 }
 

ion/src/keyboard.c

@@ -2,67 +2,45 @@
 #include <string.h>
 
 char charForKey[ION_NUMBER_OF_KEYS] = {
-  'A',
-  'B',
-  'C',
-  'D',
-  'E',
-  'F',
-  'G',
-  'H',
-  'I',
-  'J',
-  'K',
-  'L',
-  'M',
-  'N',
-  'O',
-  'P',
-  'Q',
-  'R',
-  'S',
-  'T',
-  'U',
-  'V',
-  'W',
-  'X',
-  'Y',
-  'Z',
-  '0',
-  '1',
-  '2',
-  '3',
-  '4',
-  '5',
-  '6',
-  '7',
-  '8'
+  'A', 'B', 'C', 'D', 'E',
+  'F', 'G', 'H', 'I', 'J',
+  'K', 'L', 'M', 'N', 'O',
+  'P', 'Q', 'R', 'S', 'T',
+  'U', 'V', 'W', 'X', 'Y',
+  'Z', '0', '1', '2', '3',
+  '4', '5', '6', '7', '8'
 };
 
 char ion_getchar() {
+  // Let's start by saving which keys we've seen up
+  bool key_seen_up[ION_NUMBER_OF_KEYS];
+  for (ion_key_t k=0; k<ION_NUMBER_OF_KEYS; k++) {
+    key_seen_up[k] = !ion_key_down(k);
+  }
+
+  // Wait a little to debounce the button.
+  // FIXME: REAL SLEEP
+  for (int i=0;i<10000;i++) {
+  }
+  /* Let's discard the keys we previously saw up but which aren't anymore: those
+   * were probably bouncing! */
+  for (ion_key_t k=0; k<ION_NUMBER_OF_KEYS; k++) {
+    key_seen_up[k] &= !ion_key_down(k);
+  }
+
   while (1) {
-    ion_sleep();
-    for (ion_key_t k=0;k<ION_NUMBER_OF_KEYS; k++) {
-      if (ion_key_state(k)) {
-        return charForKey[k];
+    for (ion_key_t k=0; k<ION_NUMBER_OF_KEYS; k++) {
+      if (ion_key_down(k)) {
+        if (key_seen_up[k]) {
+          return charForKey[k];
+        }
+      } else {
+        key_seen_up[k] = 1;
       }
     }
+    ion_sleep();
+    // FIXME: REAL SLEEP
+    for (int i=0;i<10000;i++) {
+    }
   }
-  /*
-     bool key_states[ION_NUMBER_OF_KEYS];
-     memcpy(key_states, ion_key_states, ION_NUMBER_OF_KEYS);
-     while (1) {
-     for (int k=0; k<ION_NUMBER_OF_KEYS; k++) {
-     if (ion_key_states[k]) {
-     if (!key_states[k]) {
-     return charForKey[k];
-     }
-     } else {
-// Key k is down. So if we ever see it up, we'll want to return a char.
-key_states[k] = 0;
-}
-}
-ion_sleep();
-}
-*/
 }