Implement support for keyboard layers

2 files changed, 50 insertions, 13 deletions

diff --git a/pit.c b/pit.c
index 1241766..58359b7 100644
--- a/pit.c
+++ b/pit.c
@@ -71,17 +71,33 @@ static const struct gpio rows[] = {
 };
 
 /* COL AND ROW SWAPPED!!! */
-static enum keycode keymap[ARRLEN(rows)][ARRLEN(cols)] = {
-	{ /* S01 */ KEY_ESCAPE, KEY_1,		KEY_2,		KEY_3,		KEY_4,		KEY_5,		KEY_6,		KEY_7,		KEY_8, },
-	{ /* S10 */ KEY_9,	KEY_0,		KEY_MINUS,	KEY_EQUAL,	KEY_NONE,	KEY_BACKSPACE,	KEY_GRAVE,	KEY_TAB,	KEY_Q, },
-	{ /* S19 */ KEY_W,	KEY_E,		KEY_R,		KEY_T,		KEY_Y,		KEY_U,		KEY_I,		KEY_O,		KEY_P, },
-	{ /* S28 */ KEY_LSQUARE, KEY_RSQUARE,	KEY_NONE,	KEY_DELETE,	KEY_CAPSLK,	KEY_A,		KEY_S,		KEY_D,		KEY_F, },
-	{ /* S37 */ KEY_G,	KEY_H,		KEY_J,		KEY_K,		KEY_L,		KEY_SEMICOLON,	KEY_QUOTE,	KEY_BACKSLASH,	KEY_ENTER, },
-	{ /* S46 */ KEY_PGUP,	KEY_LSHIFT,	KEY_NU_BACKSLASH, KEY_Z,	KEY_X,		KEY_C,		KEY_V,		KEY_B,		KEY_N, },
-	{ /* S55 */ KEY_M,	KEY_COMMA,	KEY_PERIOD,	KEY_SLASH,	KEY_RSHIFT,	KEY_UP,		KEY_PGDN,	KEY_LCTRL,	KEY_LGUI, },
-	{ /* S64 */ KEY_LALT,	KEY_SPACE,	KEY_RALT,	KEY_NONE,	KEY_RCTRL,	KEY_LEFT,	KEY_DOWN,	KEY_RIGHT,	KEY_NONE, },
+static enum keycode keymap[2][ARRLEN(rows)][ARRLEN(cols)] = {
+	{
+		{ /* S01 */ KEY_ESCAPE, KEY_1,		KEY_2,		KEY_3,		KEY_4,		KEY_5,		KEY_6,		KEY_7,		KEY_8, },
+		{ /* S10 */ KEY_9,	KEY_0,		KEY_MINUS,	KEY_EQUAL,	KEY_NONE,	KEY_BACKSPACE,	KEY_GRAVE,	KEY_TAB,	KEY_Q, },
+		{ /* S19 */ KEY_W,	KEY_E,		KEY_R,		KEY_T,		KEY_Y,		KEY_U,		KEY_I,		KEY_O,		KEY_P, },
+		{ /* S28 */ KEY_LSQUARE,KEY_RSQUARE,	KEY_NONE,	KEY_DELETE,	KEY_CAPSLK,	KEY_A,		KEY_S,		KEY_D,		KEY_F, },
+		{ /* S37 */ KEY_G,	KEY_H,		KEY_J,		KEY_K,		KEY_L,		KEY_SEMICOLON,	KEY_QUOTE,	KEY_BACKSLASH,	KEY_ENTER, },
+		{ /* S46 */ KEY_PGUP,	KEY_LSHIFT,	KEY_NU_BACKSLASH,KEY_Z,		KEY_X,		KEY_C,		KEY_V,		KEY_B,		KEY_N, },
+		{ /* S55 */ KEY_M,	KEY_COMMA,	KEY_PERIOD,	KEY_SLASH,	KEY_RSHIFT,	KEY_UP,		KEY_PGDN,	KEY_LCTRL,	KEY_LGUI, },
+		{ /* S64 */ KEY_LALT,	KEY_SPACE,	KEY_RALT,	KEY_LAYER1,	KEY_RCTRL,	KEY_LEFT,	KEY_DOWN,	KEY_RIGHT,	KEY_NONE, },
+	}, {
+		{ /* S01 */ KEY_ESCAPE, KEY_F1,		KEY_F2,		KEY_F3,		KEY_F4,		KEY_F5,		KEY_F6,		KEY_F7,		KEY_F8, },
+		{ /* S10 */ KEY_F9,	KEY_F10,	KEY_F11,	KEY_F12,	KEY_NONE,	KEY_BACKSPACE,	KEY_GRAVE,	KEY_TAB,	KEY_Q, },
+		{ /* S19 */ KEY_W,	KEY_E,		KEY_R,		KEY_T,		KEY_Y,		KEY_U,		KEY_I,		KEY_O,		KEY_P, },
+		{ /* S28 */ KEY_LSQUARE, KEY_RSQUARE,	KEY_NONE,	KEY_INSERT,	KEY_CAPSLK,	KEY_A,		KEY_S,		KEY_D,		KEY_F, },
+		{ /* S37 */ KEY_G,	KEY_H,		KEY_J,		KEY_K,		KEY_L,		KEY_SEMICOLON,	KEY_QUOTE,	KEY_BACKSLASH,	KEY_ENTER, },
+		{ /* S46 */ KEY_HOME,	KEY_LSHIFT,	KEY_NU_BACKSLASH,KEY_Z,		KEY_X,		KEY_C,		KEY_V,		KEY_B,		KEY_N, },
+		{ /* S55 */ KEY_M,	KEY_COMMA,	KEY_PERIOD,	KEY_SLASH,	KEY_RSHIFT,	KEY_UP,		KEY_END,	KEY_LCTRL,	KEY_LGUI, },
+		{ /* S64 */ KEY_LALT,	KEY_SPACE,	KEY_APPLICATION,KEY_NONE,	KEY_MENU,	KEY_LEFT,	KEY_DOWN,	KEY_RIGHT,	KEY_NONE, },
+	}
 };
 
+static enum keycode keydown[ARRLEN(cols)][ARRLEN(rows)];
+
+static unsigned char prevlayer;
+static unsigned char layer;
+
 void pit_setup(void)
 {
 	/* Set up ports (could be done with GPC registers */
@@ -121,13 +137,32 @@ static uint8_t kstates[ARRLEN(cols)][ARRLEN(rows)] = { 0 };
 static void key_state(int col, int row, bool state)
 {
 	uint8_t kstate;
+	enum keycode keycode;
 
 	kstate = kstates[col][row] = kstates[col][row] << 1 | state;
 
-	if (kstate == 0x7f)
-		usb_endpt1_setkey(keymap[row][col], true);
-	else if (kstate == 0x80)
-		usb_endpt1_setkey(keymap[row][col], false);
+	if (kstate == 0x7f) {
+		keycode = keymap[layer][row][col];
+		keydown[col][row] = keycode;
+		if (keycode < KEY_LAYER0) {
+			usb_endpt1_setkey(keycode, true);
+			return;
+		}
+		prevlayer = layer;
+		layer = keycode - KEY_LAYER0;
+	} else if (kstate == 0x80) {
+		keycode = keydown[col][row];
+		if (keycode < KEY_LAYER0) {
+			usb_endpt1_setkey(keycode, false);
+			return;
+		}
+		/*
+		 * TODO: This will actually break with more than 2 layers
+		 * needs a layer stack and also some special handling for letting go of
+		 * previous layer keys mid-press.
+		 */
+		layer = prevlayer;
+	}
 }
 
 void pit0_isr(void)
diff --git a/usb/keycodes.h b/usb/keycodes.h
index b1eec72..e43ae26 100644
--- a/usb/keycodes.h
+++ b/usb/keycodes.h
@@ -218,6 +218,8 @@ enum keycode {
 	KEY_RSHIFT,
 	KEY_RALT,
 	KEY_RGUI,
+	KEY_LAYER0 = 0xf00,
+	KEY_LAYER1,
 };
 _Static_assert(KEY_EXSEL == 0xa4, "Keycodes enum is broken");
 _Static_assert(KEY_KP_HEX == 0xdd, "Keycodes enum is broken");