From 458cb000f33527cef99c316d6fc3ba6623369a1a Mon Sep 17 00:00:00 2001
From: Tim Crawford <tcrawford@system76.com>
Date: Mon, 2 Aug 2021 11:56:47 -0600
Subject: [PATCH] kbscan: Use u8 for array access

The index will never be negative and will never exceed 255. Change them
from i16 to u8 so SDCC will generate more efficient code.

Signed-off-by: Tim Crawford <tcrawford@system76.com>
---
 src/board/system76/common/kbscan.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/src/board/system76/common/kbscan.c b/src/board/system76/common/kbscan.c
index 780be1b..e6833f9 100644
--- a/src/board/system76/common/kbscan.c
+++ b/src/board/system76/common/kbscan.c
@@ -30,11 +30,11 @@ uint8_t kbscan_matrix[KM_OUT] = { 0 };
 
 uint8_t sci_extra = 0;
 
-static inline bool matrix_position_is_esc(int16_t row, int16_t col) {
+static inline bool matrix_position_is_esc(uint8_t row, uint8_t col) {
     return (row == MATRIX_ESC_OUTPUT) && (col == MATRIX_ESC_INPUT);
 }
 
-static inline bool matrix_position_is_fn(int16_t row, int16_t col) {
+static inline bool matrix_position_is_fn(uint8_t row, uint8_t col) {
     return (row == MATRIX_FN_OUTPUT) && (col == MATRIX_FN_INPUT);
 }
 
@@ -60,7 +60,7 @@ void kbscan_init(void) {
 // Debounce time in milliseconds
 #define DEBOUNCE_DELAY 15
 
-static uint8_t kbscan_get_row(int16_t i) {
+static uint8_t kbscan_get_row(uint8_t i) {
     // Report all keys as released when lid is closed
     if (!lid_state) {
         return 0;
@@ -118,7 +118,7 @@ static uint8_t kbscan_get_row(int16_t i) {
 }
 
 #if KM_NKEY
-static bool kbscan_has_ghost_in_row(int16_t row, uint8_t rowdata) {
+static bool kbscan_has_ghost_in_row(uint8_t row, uint8_t rowdata) {
     // Use arguments
     row = row;
     rowdata = rowdata;
@@ -129,21 +129,21 @@ static inline bool popcount_more_than_one(uint8_t rowdata) {
     return rowdata & (rowdata - 1);
 }
 
-static uint8_t kbscan_get_real_keys(int16_t row, uint8_t rowdata) {
+static uint8_t kbscan_get_real_keys(uint8_t row, uint8_t rowdata) {
     // Remove any "active" blanks from the matrix.
     uint8_t realdata = 0;
     for (uint8_t col = 0; col < KM_IN; col++) {
         // This tests the default keymap intentionally, to avoid blanks in the
         // dynamic keymap
         if (KEYMAP[0][row][col] && (rowdata & BIT(col))) {
-            realdata |=  BIT(col);
+            realdata |= BIT(col);
         }
     }
 
     return realdata;
 }
 
-static bool kbscan_has_ghost_in_row(int16_t row, uint8_t rowdata) {
+static bool kbscan_has_ghost_in_row(uint8_t row, uint8_t rowdata) {
     rowdata = kbscan_get_real_keys(row, rowdata);
 
     // No ghosts exist when  less than 2 keys in the row are active.
@@ -152,7 +152,7 @@ static bool kbscan_has_ghost_in_row(int16_t row, uint8_t rowdata) {
     }
 
     // Check against other rows to see if more than one column matches.
-    for (int16_t i = 0; i < KM_OUT; i++) {
+    for (uint8_t i = 0; i < KM_OUT; i++) {
         uint8_t otherrow = kbscan_get_real_keys(i, kbscan_get_row(i));
         if (i != row && popcount_more_than_one(otherrow & rowdata)) {
             return true;
@@ -315,8 +315,7 @@ void kbscan_event(void) {
         }
     }
 
-    int16_t i;
-    for (i = 0; i < KM_OUT; i++) {
+    for (uint8_t i = 0; i < KM_OUT; i++) {
         uint8_t new = kbscan_get_row(i);
         uint8_t last = kbscan_matrix[i];
         if (new != last) {
@@ -331,8 +330,7 @@ void kbscan_event(void) {
             }
 
             // A key was pressed or released
-            int16_t j;
-            for (j = 0; j < KM_IN; j++) {
+            for (uint8_t j = 0; j < KM_IN; j++) {
                 bool new_b = new & BIT(j);
                 bool last_b = last & BIT(j);
                 if (new_b != last_b) {