add a dynamic setting for keyboard scan frequency

The repeat delays of getkey() are adjusted automatically, however a
repeat that is currently going on might be affected.

Also, repeat delays are always approximated as a whole number of
keyboard scans so an increase in scan frequency can impact the speed at
which repeats are emitted.

include/gint/hardware.h

@@ -64,7 +64,7 @@ void hw_detect(void);
 #define HWURAM   6    /* Userspace RAM */
 #define HWETMU   7    /* Extra Timer Units */
 #define HWKBD    8    /* Keyboard */
-#define HWKBDSF  9    /* Keyboard Scan Frequency (set iff HWKBD is loaded) */
+#define HWKBDSF       /* Deprecated: use keysc_scan_frequency() */
 #define HWDD     10   /* Display Driver */
 
 /*

include/gint/keyboard.h

@@ -120,12 +120,28 @@ enum
 #define KEYBOARD_QUEUE_SIZE 32
 #endif
 
-/* Keyboard frequency analysis, must be at least 64 for the keyboard to work,
-   and at most 32768 for the extra timer to support it. Better if a power of 2.
-   TODO: Add a runtime setting for KEYBOARD_SCAN_FREQUENCY */
-#ifndef KEYBOARD_SCAN_FREQUENCY
-#define KEYBOARD_SCAN_FREQUENCY 128
-#endif
+/* Keyboard frequency analysis is a runtime setting since gint 2.4. This macro
+   is preserved for compatibility until gint 3. */
+#define KEYBOARD_SCAN_FREQUENCY keysc_scan_frequency()
+
+//---
+//  Scan frequency settings
+//---
+
+/* keysc_scan_frequency(): Get the current keyboard scan frequency in Hertz */
+int keysc_scan_frequency(void);
+
+/* keysc_scan_frequency_us(): Get keyboard scan delay in microseconds */
+uint32_t keysc_scan_frequency_us(void);
+
+/* keysc_set_scan_frequency(): Set the keyboard scan frequency in Hertz
+
+   The new frequency must be at least 64 for the keyboard to work reliably, and
+   at most 32768 for the underlying ETMU to support it. Out-of-range values are
+   forced to the closest valid value.
+
+   @freq  New scan frequency, in Hertz */
+void keysc_set_scan_frequency(int freq);
 
 //---
 //	Event-level functions

src/keysc/getkey.c

@@ -5,15 +5,18 @@
 #include <gint/keyboard.h>
 #include <gint/gint.h>
 #include <gint/defs/types.h>
+#include "getkey.h"
 
 #ifdef FX9860G
 #include <gint/drivers/t6k11.h>
 #endif
 
 /* Delay between a key press and the first repeat, in scan intervals */
-static int rep_first = 64;
+static int rep_first = 51;
 /* Delay between subsequent repeats, in scan intervals */
-static int rep_next = 8;
+static int rep_next = 5;
+/* Same in milliseconds (values supplied by the user */
+static int rep_first_ms = 400, rep_next_ms = 40;
 
 /* Repeat filter function */
 static int (*filter_function)(int key, int duration, int count) = NULL;
@@ -132,7 +135,7 @@ key_event_t getkey_opt(int opt, volatile int *timeout)
 			/* Delay repeat by set amount */
 			if(s > 0)
 			{
-				s = (s * KEYBOARD_SCAN_FREQUENCY) / 1000;
+				s = (s * keysc_scan_frequency()) / 1000;
 				rep_delay += s;
 				break;
 			}
@@ -165,8 +168,11 @@ key_event_t getkey_opt(int opt, volatile int *timeout)
 /* getkey_repeat(): Set repeat delays for getkey() */
 void getkey_repeat(int first, int next)
 {
-	rep_first = (first * KEYBOARD_SCAN_FREQUENCY) / 1000;
-	rep_next = (next * KEYBOARD_SCAN_FREQUENCY) / 1000;
+	rep_first_ms = first;
+	rep_next_ms = next;
+
+	rep_first = (first * keysc_scan_frequency()) / 1000;
+	rep_next = (next * keysc_scan_frequency()) / 1000;
 }
 
 /* getkey_repeat_filter(): Set the repeat filter function */
@@ -174,3 +180,9 @@ void getkey_repeat_filter(int (*filter)(int key, int duration, int count))
 {
 	filter_function = filter;
 }
+
+/* Refresh repeat delays after a change in keyboard scan frequency */
+void getkey_refresh_delays(void)
+{
+	getkey_repeat(rep_first_ms, rep_next_ms);
+}

src/keysc/getkey.h

@@ -0,0 +1,11 @@
+//---
+//	gint:keysc:getkey - Internal interface to getkey()
+//---
+
+#ifndef GINT_KEYSC_GETKEY
+#define GINT_KEYSC_GETKEY
+
+/* Refresh repeat delays after a change in keyboard scan frequency */
+void getkey_refresh_delays(void);
+
+#endif /* GINT_KEYSC_GETKEY */

src/keysc/keysc.c

@@ -13,8 +13,16 @@
 #include <gint/drivers/iokbd.h>
 #include <gint/hardware.h>
 
+#include "getkey.h"
+
 #include <stdarg.h>
 
+/* Keyboard scan frequency in Hertz. Start with 128 Hz, this frequency *must
+   be high* for the keyboard to work! */
+static int scan_frequency = 128;
+/* Keyboard scanner timer */
+static int keysc_tid = -1;
+
 //---
 //	Keyboard buffer
 //---
@@ -78,6 +86,38 @@ static int buffer_poll(driver_event_t *ev)
 	return 0;
 }
 
+//---
+//	Keyboard scanning
+//---
+
+/* keysc_scan_frequency(): Get the current keyboard scan frequency in Hertz */
+int keysc_scan_frequency(void)
+{
+	return scan_frequency;
+}
+
+/* keysc_scan_frequency_us(): Get keyboard scan delay in microseconds */
+uint32_t keysc_scan_frequency_us(void)
+{
+	int delay = 1000000 / scan_frequency;
+	if(delay == 0) delay = 1;
+	return delay;
+}
+
+/* keysc_set_scan_frequency(): Set the keyboard scan frequency in Hertz */
+void keysc_set_scan_frequency(int freq)
+{
+	if(freq < 64) freq = 64;
+	if(freq > 32768) freq = 32768;
+	scan_frequency = freq;
+
+	if(keysc_tid < 0) return;
+	uint32_t TCOR = timer_delay(keysc_tid, keysc_scan_frequency_us(), 0);
+	timer_reload(keysc_tid, TCOR);
+
+	getkey_refresh_delays();
+}
+
 /* keysc_frame(): Generate driver events from KEYSC state */
 static void keysc_frame(void)
 {
@@ -258,20 +298,14 @@ static int callback(void)
 /* init() - setup the support timer */
 static void init(void)
 {
-	/* Configure the timer to do 128 keyboard scans per second. This
-	   frequency *must* be high for the KEYSC interface to work! */
-	int delay = 1000000 / KEYBOARD_SCAN_FREQUENCY;
-	if(!delay) delay = 1;
-
 	/* Set the default repeat times (milliseconds) */
 	getkey_repeat(400, 40);
 
 	/* The timer will be stopped when the timer driver is unloaded */
-	int tid = timer_setup(TIMER_ANY, delay, callback);
-	if(tid >= 0) timer_start(tid);
+	keysc_tid = timer_setup(TIMER_ANY,keysc_scan_frequency_us(),callback);
+	if(keysc_tid >= 0) timer_start(keysc_tid);
 
 	gint[HWKBD] = HW_LOADED | (isSH3() ? HWKBD_IO : HWKBD_KSI);
-	gint[HWKBDSF] = KEYBOARD_SCAN_FREQUENCY;
 }
 
 //---