borg_hw_lolshield.c: counter intervals now calculated entirely at

compile time, saving 154 bytes

src/borg_hw/borg_hw_lolshield.c

@@ -125,17 +125,6 @@ unsigned char pixmap[NUMPLANE][NUM_ROWS][LINEBYTES];
 #   error no support for this chip
 #endif
 
-
-#ifndef BRIGHTNESS
-#	define BRIGHTNESS 127 /* full brightness by default */
-#elif BRIGHTNESS < 0 || BRIGHTNESS > 127
-#	error BRIGHTNESS must be between 0 and 127
-#endif
-
-#define BRIGHTNESSPERCENT ((BRIGHTNESS * BRIGHTNESS + 8ul) / 16ul)
-#define M (TICKS << FASTSCALERSHIFT) * BRIGHTNESSPERCENT /*10b*/
-#define C(x) ((M * (unsigned long)(x * 1024) + (1 << 19)) >> 20) /*10b+10b-20b=0b*/
-
 #if NUMPLANE < 8
 uint8_t const prescaler[NUMPLANE + 1] = {
 	FASTPRESCALER,
@@ -163,81 +152,100 @@ uint8_t const prescaler[NUMPLANE + 1] = {
 uint8_t prescaler[NUMPLANE + 1] = {0};
 #endif
 
-uint8_t counts[NUMPLANE + 1] = {0};
+/* adjust brightness in the menuconfig, this is just a fallback */
+#ifndef BRIGHTNESS
+#	define BRIGHTNESS 127 /* full brightness by default */
+#elif BRIGHTNESS < 0 || BRIGHTNESS > 127
+#	error BRIGHTNESS must be between 0 and 127
+#endif
 
-/**
- *  Set the overall brightness of the screen from 0 (off) to 127 (full on).
- */
-static void setBrightness()
-{
-	/*   ---- This needs review! Please review. -- thilo  */
-	// set up page counts
-	uint8_t i;
+#define BRIGHTNESSPERCENT ((BRIGHTNESS * BRIGHTNESS + 8ul) / 16ul)
+#define M (TICKS << FASTSCALERSHIFT) * BRIGHTNESSPERCENT /*10b*/
+#define C(x) ((M * (unsigned long)(x * 1024UL) + (1UL << 19)) >> 20) /*10b+10b-20b=0b*/
+
+#define COUNT(u, v) (256 - (((C(v) - C(u)) != 0) ? (C(v) - C(u)) : 1))
+#define LAST_COUNT(u) (256 - (((TICKS - (C(u) >> FASTSCALERSHIFT)) != 0) ? \
+		(TICKS - (C(u) >> FASTSCALERSHIFT)) : 1))
 
-	// NOTE: The argument of C() is calculated as follows:
-	// pow((double)x / (double)NUMPLANE, 1.8) with 0 <= x <= NUMPLANE
-	// Changing the scale of 1.8 invalidates any tables above!
 #if NUMPLANE < 8
-	int const temp_counts[NUMPLANE + 1] = {
-		0.000000000000000000000000000,
-#	if NUMPLANE == 2
-		C(0.287174588749258719033719),
+// NOTE: The argumentS of COUNT() are calculated as follows:
+// pow((double)x / (double)NUMPLANE, 1.8) with 0 <= x <= NUMPLANE
+// Changing the scale of 1.8 invalidates any tables above!
+uint8_t const counts[NUMPLANE + 1] = {
+#	if NUMPLANE == 1
+		COUNT(0.000000000000000000000000, 1.000000000000000000000000),
+#	elif NUMPLANE == 2
+		COUNT(0.000000000000000000000000, 0.287174588749258719033719),
+		COUNT(0.287174588749258719033719, 1.000000000000000000000000),
 #	elif NUMPLANE == 3
-		C(0.138414548846168578011273),
-		C(0.481987453865643789008288),
+		COUNT(0.000000000000000000000000, 0.138414548846168578011273),
+		COUNT(0.138414548846168578011273, 0.481987453865643789008288),
+		COUNT(0.481987453865643789008288, 1.000000000000000000000000),
 #	elif NUMPLANE == 4
-		C(0.082469244423305887448095),
-		C(0.287174588749258719033719),
-		C(0.595813410589956848895099),
+		COUNT(0.000000000000000000000000, 0.082469244423305887448095),
+		COUNT(0.082469244423305887448095, 0.287174588749258719033719),
+		COUNT(0.287174588749258719033719, 0.595813410589956848895099),
+		COUNT(0.595813410589956848895099, 1.000000000000000000000000),
 #	elif NUMPLANE == 5
-		C(0.055189186458448592775827),
-		C(0.192179909437029006191722),
-		C(0.398723883569384374148115),
-		C(0.669209313658414961523135),
+		COUNT(0.000000000000000000000000, 0.055189186458448592775827),
+		COUNT(0.055189186458448592775827, 0.192179909437029006191722),
+		COUNT(0.192179909437029006191722, 0.398723883569384374148115),
+		COUNT(0.398723883569384374148115, 0.669209313658414961523135),
+		COUNT(0.669209313658414961523135, 1.000000000000000000000000),
 #	elif NUMPLANE == 6
-		C(0.039749141141812646682574),
-		C(0.138414548846168578011273),
-		C(0.287174588749258719033719),
-		C(0.481987453865643789008288),
-		C(0.720234228706005730202833),
+		COUNT(0.000000000000000000000000, 0.039749141141812646682574),
+		COUNT(0.039749141141812646682574, 0.138414548846168578011273),
+		COUNT(0.138414548846168578011273, 0.287174588749258719033719),
+		COUNT(0.287174588749258719033719, 0.481987453865643789008288),
+		COUNT(0.481987453865643789008288, 0.720234228706005730202833),
+		COUNT(0.720234228706005730202833, 1.000000000000000000000000),
 #	elif NUMPLANE == 7
-		C(0.030117819624378608378557),
-		C(0.104876339357015443964904),
-		C(0.217591430058779483625031),
-		C(0.365200625214741059210155),
-		C(0.545719579451565794947498),
-		C(0.757697368024318751444923),
+		COUNT(0.000000000000000000000000, 0.030117819624378608378557),
+		COUNT(0.030117819624378608378557, 0.104876339357015443964904),
+		COUNT(0.104876339357015443964904, 0.217591430058779483625031),
+		COUNT(0.217591430058779483625031, 0.365200625214741059210155),
+		COUNT(0.365200625214741059210155, 0.545719579451565794947498),
+		COUNT(0.545719579451565794947498, 0.757697368024318751444923),
+		COUNT(0.757697368024318751444923, 1.000000000000000000000000),
 #	endif
-		C(1.000000000000000000000000),
-	};
+		LAST_COUNT(1.0)
+};
 #else
+uint8_t counts[NUMPLANE + 1];
+#endif
+
+
+#if NUMPLANE >= 8
+/**
+ *  Set the overall brightness of the screen from 0 (very dim) to 127 (full on).
+ */
+static void setBrightness()
+{
 #	warning "NUMPLANE >= 8 links floating point stuff into the image"
+	/*   ---- This needs review! Please review. -- thilo  */
+	// set up page counts
+	uint8_t i;
 	// NOTE: Changing "scale" invalidates any tables above!
 	const float scale = 1.8f;
 	int temp_counts[NUMPLANE + 1] = {0};
-
 	for (i = 1; i < (NUMPLANE + 1); i++) {
 		temp_counts[i] = C(pow(i / (float)(NUMPLANE), scale));
 	}
-#endif
 
 	// Compute on time for each of the pages
 	// Use the fast timer; slow timer is only useful for < 3 shades.
 	for (i = 0; i < NUMPLANE; i++) {
 		int interval = temp_counts[i + 1] - temp_counts[i];
 		counts[i] = 256 - (interval ? interval : 1);
-#if NUMPLANE >= 8
 		prescaler[i] = FASTPRESCALER;
-#endif
 	}
 
 	// Compute off time
 	int interval = TICKS - (temp_counts[i] >> FASTSCALERSHIFT);
 	counts[i] = 256 - (interval ? interval : 1);
-#if NUMPLANE >= 8
-		prescaler[i] = SLOWPRESCALER;
-#endif
+	prescaler[i] = SLOWPRESCALER;
 }
+#endif
 
 /**
  * Distributes the framebuffer content among current cycle pins.
@@ -930,7 +938,9 @@ void borg_hw_init() {
 	OCR1A = 256;
 #endif
 
+#if NUMPLANE >= 8
 	setBrightness();
+#endif
 
 	// Then start the display
 #if defined (__AVR_ATmega48__)   || \