From a08bdbf124f86412719166796f5e7dacf3c273cd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=A1szl=C3=B3=20Monda?= <laci@monda.hu>
Date: Thu, 20 Oct 2016 19:29:36 +0200
Subject: [PATCH] Reverse the diodes and optimize key scanning as much as
 possible.

---
 shared/key_matrix.c | 36 +++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/shared/key_matrix.c b/shared/key_matrix.c
index daf2ab8..75c0b67 100644
--- a/shared/key_matrix.c
+++ b/shared/key_matrix.c
@@ -3,31 +3,37 @@
 
 void KeyMatrix_Init(key_matrix_t *keyMatrix)
 {
-    for (uint8_t col_i=0; col_i<keyMatrix->colNum; col_i++) {
-        key_matrix_pin_t col = keyMatrix->cols[col_i];
-        CLOCK_EnableClock(col.clock);
-        PORT_SetPinConfig(col.port, col.pin,
+    for (key_matrix_pin_t *row = keyMatrix->rows; row < keyMatrix->rows + keyMatrix->rowNum; row++) {
+        CLOCK_EnableClock(row->clock);
+        PORT_SetPinConfig(row->port, row->pin,
                           &(port_pin_config_t){.pullSelect=kPORT_PullDisable, .mux=kPORT_MuxAsGpio});
-        GPIO_PinInit(col.gpio, col.pin, &(gpio_pin_config_t){kGPIO_DigitalOutput, 0});
+        GPIO_PinInit(row->gpio, row->pin, &(gpio_pin_config_t){kGPIO_DigitalOutput, 0});
     }
 
-    for (uint8_t row_i=0; row_i<keyMatrix->rowNum; row_i++) {
-        key_matrix_pin_t row = keyMatrix->rows[row_i];
-        CLOCK_EnableClock(row.clock);
-        PORT_SetPinConfig(row.port, row.pin,
+    for (key_matrix_pin_t *col = keyMatrix->cols; col < keyMatrix->cols + keyMatrix->colNum; col++) {
+        CLOCK_EnableClock(col->clock);
+        PORT_SetPinConfig(col->port, col->pin,
                           &(port_pin_config_t){.pullSelect=kPORT_PullDown, .mux=kPORT_MuxAsGpio});
-        GPIO_PinInit(row.gpio, row.pin, &(gpio_pin_config_t){kGPIO_DigitalInput});
+        GPIO_PinInit(col->gpio, col->pin, &(gpio_pin_config_t){kGPIO_DigitalInput});
     }
 }
 
 void KeyMatrix_Scan(key_matrix_t *keyMatrix)
 {
-    for (uint8_t col=0; col<keyMatrix->colNum; col++) {
-        GPIO_WritePinOutput(keyMatrix->cols[col].gpio, keyMatrix->cols[col].pin, 1);
-        for (uint8_t row=0; row<keyMatrix->rowNum; row++) {
-            keyMatrix->keyStates[row*keyMatrix->colNum + col] = GPIO_ReadPinInput(keyMatrix->rows[row].gpio, keyMatrix->rows[row].pin);
+    uint8_t *keyState = keyMatrix->keyStates;
+
+    key_matrix_pin_t *rowEnd = keyMatrix->rows + keyMatrix->rowNum;
+    for (key_matrix_pin_t *row = keyMatrix->rows; row<rowEnd; row++) {
+        GPIO_Type *rowGpio = row->gpio;
+        uint32_t rowPin = row->pin;
+        GPIO_WritePinOutput(rowGpio, rowPin, 1);
+
+        key_matrix_pin_t *colEnd = keyMatrix->cols + keyMatrix->colNum;
+        for (key_matrix_pin_t *col = keyMatrix->cols; col<colEnd; col++) {
+            *(keyState++) = GPIO_ReadPinInput(col->gpio, col->pin);
         }
-        GPIO_WritePinOutput(keyMatrix->cols[col].gpio, keyMatrix->cols[col].pin, 0);
+
+        GPIO_WritePinOutput(rowGpio, rowPin, 0);
         for (volatile uint32_t i=0; i<100; i++); // Wait for the new port state to settle. This avoid bogus key state detection.
     }
 }