[PATCH 5/8] Support for specifying ST key modifiers in the mapping file

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Single PC key can map into ST scancode with multiple ST modifiers.

Because modifiers are stored as a bitmask, ST modifier order given in
mapping file is ignored.  Modifiers are always pressed in same order
before the scancode, and released in same order after it.

Because modifier keys can now come & be specified both as individual
ST keys, and as modifiers to other scancodes, presses & releases for
each scancode are now counted ( not just true & false values).

Inspired by Vincent Barilliot's patch.
---
 src/keymap.c | 138 +++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 128 insertions(+), 10 deletions(-)

diff --git a/src/keymap.c b/src/keymap.c
index d262eb78..71a6d0dd 100644
--- a/src/keymap.c
+++ b/src/keymap.c
@@ -51,9 +51,23 @@ typedef struct
 	SDL_Scancode scancode;
 } SDLKey;
 
+static const struct
+{
+	const char *name;
+	uint8_t scancode;
+	uint8_t mod;
+} ST_Modifiers[] = {
+	{"CONTROL", ST_CONTROL,   0x01},
+	{"LSHIFT",  ST_LSHIFT,    0x02},
+	{"RSHIFT",  ST_RSHIFT,    0x04},
+	{"ALT",     ST_ALTERNATE, 0x08},
+};
+
 typedef struct
 {
 	uint8_t scancode;
+	/* key modifiers matching ST_Modifiers[].mod bit values */
+	uint8_t mods;
 } ST_Key;
 
 /* Key mappings: pair SDL key definition with ST key */
@@ -453,6 +467,7 @@ static ST_Key* Keymap_RemapKeyToSTKey(const SDL_Keysym* pKeySym)
 
 	/* check for UpdateMapping() */
 	assert(scancode < ARRAY_SIZE(KeysDown));
+	memset(KeysDown+scancode, 0, sizeof(*KeysDown));
 
 	/* Check for keypad first so we can handle numlock */
 	if (ConfigureParams.Keyboard.nKeymapType != KEYMAP_LOADED &&
@@ -483,6 +498,7 @@ static ST_Key* Keymap_RemapKeyToSTKey(const SDL_Keysym* pKeySym)
 			if (mapping->pc.scancode != scancode)
 				continue;
 
+			KeysDown[scancode].mods = mapping->st.mods;
 			return UpdateMapping("keymap", scancode,
 					     mapping->st.scancode);
 		}
@@ -528,6 +544,32 @@ static bool HostSpecToKeymap(const char *spec, KeyMapping* mapping)
 }
 
 
+/*-----------------------------------------------------------------------*/
+/**
+ * Parse modifier name from 'name' and return 'mods' value with
+ * corresponding bit added to it, or return zero if there was no match
+ */
+static uint8_t AddSTModifier(uint8_t mods, const char *name)
+{
+	uint8_t mod, i;
+	for (i = 0; i < ARRAY_SIZE(ST_Modifiers); i++)
+	{
+		if (strcmp(ST_Modifiers[i].name, name) != 0)
+			continue;
+
+		mod = ST_Modifiers[i].mod;
+		if (mod & mods)
+		{
+			Log_Printf(LOG_WARN, "ST modifier '%s' specified twice\n", name);
+			return 0;
+		}
+		return (mods | mod);
+	}
+	Log_Printf(LOG_ERROR, "unknown/unsupported ST modifier '%s'\n", name);
+	return 0;
+}
+
+
 /*-----------------------------------------------------------------------*/
 /**
  * Fill "mapping" KeyMapping guest (ST) part based on guest "spec" string.
@@ -535,19 +577,52 @@ static bool HostSpecToKeymap(const char *spec, KeyMapping* mapping)
  */
 static bool GuestSpecToKeymap(const char *spec, KeyMapping* mapping)
 {
-	int key;
+	char buf[64], *token, *saveptr, *endptr;
+	uint8_t scancode, mods;
+
 	if (!spec)
 		return false;
-
-	key = atoi(spec);
-	if (key <= 0 || key > KBD_MAX_SCANCODE)
+	if (strlcpy(buf, spec, sizeof(buf)) >= sizeof(buf))
 	{
-		Log_Printf(LOG_WARN, "Invalid ST scancode: '%s' (0 > %d < %d)\n",
-			   spec, key, KBD_MAX_SCANCODE);
+		Log_Printf(LOG_ERROR, "ST scancode spec '%s' too long\n", spec);
 		return false;
 	}
-	mapping->st.scancode = key;
-	return true;
+
+	scancode = mods = 0;
+	for (token = strtok_r(buf, "|", &saveptr);
+	     token;
+	     token = strtok_r(NULL, "|", &saveptr))
+	{
+		token = Str_Trim(token);
+		if (isalpha(token[0]))
+		{
+			mods = AddSTModifier(mods, token);
+			if (!mods)
+				return false;
+			continue;
+		}
+		if (scancode)
+		{
+			Log_Printf(LOG_WARN, "extra '%s', ST scancode already set\n", token);
+			return false;
+		}
+		scancode = strtol(token, &endptr, 10);
+		if (!scancode)
+		{
+			Log_Printf(LOG_ERROR, "invalid ST scancode '%s'\n", token);
+			return false;
+		}
+		if (*endptr)
+		{
+			Log_Printf(LOG_WARN, "'%s' garbage at end of '%s' ST scancode\n",
+				   endptr, token);
+			return false;
+		}
+	}
+	mapping->st.scancode = scancode;
+	mapping->st.mods = mods;
+
+	return (scancode > 0);
 }
 
 
@@ -724,6 +799,44 @@ static bool IsKeyTranslatable(SDL_Keycode symkey)
 }
 
 
+/*-----------------------------------------------------------------------*/
+/**
+ * Set modifiers keys indicated by bits in 'mods' up or down
+ * based on 'down'.
+ */
+static void InsertModifiers(uint8_t mods, bool down)
+{
+	uint8_t i, scancode;
+	if (!mods)
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(ST_Modifiers); i++)
+	{
+		if (!(mods & ST_Modifiers[i].mod))
+			continue;
+
+		scancode = ST_Modifiers[i].scancode;
+
+		if (down)
+		{
+			/* because modifiers may already be down
+			 * due to normal key events (or mapped
+			 * scancodes that happen to be modifiers),
+			 * KeyStates are counted
+			 */
+			if (Keyboard.KeyStates[scancode]++ > 0)
+				continue;
+		}
+		else
+		{
+			if (--Keyboard.KeyStates[scancode] > 0)
+				continue;
+		}
+		IKBD_PressSTKey(scancode, down);
+	}
+}
+
+
 /*-----------------------------------------------------------------------*/
 /**
  * User pressed a key down
@@ -756,10 +869,13 @@ void Keymap_KeyDown(const SDL_Keysym *sdlkey)
 
 	STScanCode = stkey->scancode;
 	LOG_TRACE(TRACE_KEYMAP, "key map: sym=0x%x to ST-scan=0x%02x\n", symkey, STScanCode);
+
+	assert(Keyboard.KeyStates[scancode] == 0);
+	InsertModifiers(stkey->mods, true);
 	if (!Keyboard.KeyStates[STScanCode])
 	{
 		/* Set down */
-		Keyboard.KeyStates[STScanCode] = true;
+		Keyboard.KeyStates[STScanCode]++;
 		IKBD_PressSTKey(STScanCode, true);
 	}
 }
@@ -801,11 +917,13 @@ void Keymap_KeyUp(const SDL_Keysym *sdlkey)
 
 	/* Release key (only if was pressed) */
 	STScanCode = stkey->scancode;
+	assert(Keyboard.KeyStates[STScanCode] > 0);
 	if (Keyboard.KeyStates[STScanCode])
 	{
 		IKBD_PressSTKey(STScanCode, false);
-		Keyboard.KeyStates[STScanCode] = false;
+		Keyboard.KeyStates[STScanCode]--;
 	}
+	InsertModifiers(stkey->mods, false);
 }
 
 /*-----------------------------------------------------------------------*/
-- 
2.30.2


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