Author: des
Date: Sat Jan 2 16:40:37 2016
New Revision: 293049
URL: https://svnweb.freebsd.org/changeset/base/293049
Log:
Replace the cosine table with a sine table, which (due to the vagaries of
rounding) has better spread. Implement fp16_sin() to go along with
fp16_cos(). In the rendering loop, switch from addition to subtraction
so the center of the pattern will be a trough rather than a peak. This
is completely arbitrary, of course, but looks better to me.
Modified:
head/sys/dev/syscons/plasma/fp16.c
head/sys/dev/syscons/plasma/fp16.h
head/sys/dev/syscons/plasma/plasma_saver.c
Modified: head/sys/dev/syscons/plasma/fp16.c
==============================================================================
--- head/sys/dev/syscons/plasma/fp16.c Sat Jan 2 10:07:31 2016
(r293048)
+++ head/sys/dev/syscons/plasma/fp16.c Sat Jan 2 16:40:37 2016
(r293049)
@@ -71,42 +71,66 @@ fp16_sqrt(fp16_t x)
return (y);
}
-static fp16_t fp16_cos_table[256] = {
- 65536, 65534, 65531, 65524, 65516, 65505, 65491, 65475,
- 65457, 65436, 65412, 65386, 65358, 65327, 65294, 65258,
- 65220, 65179, 65136, 65091, 65043, 64992, 64939, 64884,
- 64826, 64766, 64703, 64638, 64571, 64501, 64428, 64353,
- 64276, 64197, 64115, 64030, 63943, 63854, 63762, 63668,
- 63571, 63473, 63371, 63268, 63162, 63053, 62942, 62829,
- 62714, 62596, 62475, 62353, 62228, 62100, 61971, 61839,
- 61705, 61568, 61429, 61288, 61144, 60998, 60850, 60700,
- 60547, 60392, 60235, 60075, 59913, 59749, 59583, 59414,
- 59243, 59070, 58895, 58718, 58538, 58356, 58172, 57986,
- 57797, 57606, 57414, 57219, 57022, 56822, 56621, 56417,
- 56212, 56004, 55794, 55582, 55368, 55152, 54933, 54713,
- 54491, 54266, 54040, 53811, 53581, 53348, 53114, 52877,
- 52639, 52398, 52155, 51911, 51665, 51416, 51166, 50914,
- 50660, 50403, 50146, 49886, 49624, 49360, 49095, 48828,
- 48558, 48288, 48015, 47740, 47464, 47186, 46906, 46624,
- 46340, 46055, 45768, 45480, 45189, 44897, 44603, 44308,
- 44011, 43712, 43412, 43110, 42806, 42501, 42194, 41885,
- 41575, 41263, 40950, 40636, 40319, 40002, 39682, 39362,
- 39039, 38716, 38390, 38064, 37736, 37406, 37075, 36743,
- 36409, 36074, 35738, 35400, 35061, 34721, 34379, 34036,
- 33692, 33346, 32999, 32651, 32302, 31952, 31600, 31247,
- 30893, 30538, 30181, 29824, 29465, 29105, 28745, 28383,
- 28020, 27656, 27291, 26925, 26557, 26189, 25820, 25450,
- 25079, 24707, 24334, 23960, 23586, 23210, 22833, 22456,
- 22078, 21699, 21319, 20938, 20557, 20175, 19792, 19408,
- 19024, 18638, 18253, 17866, 17479, 17091, 16702, 16313,
- 15923, 15533, 15142, 14751, 14359, 13966, 13573, 13179,
- 12785, 12390, 11995, 11600, 11204, 10807, 10410, 10013,
- 9616, 9218, 8819, 8421, 8022, 7623, 7223, 6823,
- 6423, 6023, 5622, 5222, 4821, 4420, 4018, 3617,
- 3215, 2814, 2412, 2010, 1608, 1206, 804, 402,
+static fp16_t fp16_sin_table[256] = {
+ 0, 402, 804, 1206, 1608, 2010, 2412, 2814,
+ 3215, 3617, 4018, 4420, 4821, 5222, 5622, 6023,
+ 6423, 6823, 7223, 7623, 8022, 8421, 8819, 9218,
+ 9616, 10013, 10410, 10807, 11204, 11600, 11995, 12390,
+ 12785, 13179, 13573, 13966, 14359, 14751, 15142, 15533,
+ 15923, 16313, 16702, 17091, 17479, 17866, 18253, 18638,
+ 19024, 19408, 19792, 20175, 20557, 20938, 21319, 21699,
+ 22078, 22456, 22833, 23210, 23586, 23960, 24334, 24707,
+ 25079, 25450, 25820, 26189, 26557, 26925, 27291, 27656,
+ 28020, 28383, 28745, 29105, 29465, 29824, 30181, 30538,
+ 30893, 31247, 31600, 31952, 32302, 32651, 32999, 33346,
+ 33692, 34036, 34379, 34721, 35061, 35400, 35738, 36074,
+ 36409, 36743, 37075, 37406, 37736, 38064, 38390, 38716,
+ 39039, 39362, 39682, 40002, 40319, 40636, 40950, 41263,
+ 41575, 41885, 42194, 42501, 42806, 43110, 43412, 43712,
+ 44011, 44308, 44603, 44897, 45189, 45480, 45768, 46055,
+ 46340, 46624, 46906, 47186, 47464, 47740, 48015, 48288,
+ 48558, 48828, 49095, 49360, 49624, 49886, 50146, 50403,
+ 50660, 50914, 51166, 51416, 51665, 51911, 52155, 52398,
+ 52639, 52877, 53114, 53348, 53581, 53811, 54040, 54266,
+ 54491, 54713, 54933, 55152, 55368, 55582, 55794, 56004,
+ 56212, 56417, 56621, 56822, 57022, 57219, 57414, 57606,
+ 57797, 57986, 58172, 58356, 58538, 58718, 58895, 59070,
+ 59243, 59414, 59583, 59749, 59913, 60075, 60235, 60392,
+ 60547, 60700, 60850, 60998, 61144, 61288, 61429, 61568,
+ 61705, 61839, 61971, 62100, 62228, 62353, 62475, 62596,
+ 62714, 62829, 62942, 63053, 63162, 63268, 63371, 63473,
+ 63571, 63668, 63762, 63854, 63943, 64030, 64115, 64197,
+ 64276, 64353, 64428, 64501, 64571, 64638, 64703, 64766,
+ 64826, 64884, 64939, 64992, 65043, 65091, 65136, 65179,
+ 65220, 65258, 65294, 65327, 65358, 65386, 65412, 65436,
+ 65457, 65475, 65491, 65505, 65516, 65524, 65531, 65534,
};
/*
+ * Compute the sine of theta.
+ */
+fp16_t
+fp16_sin(fp16_t theta)
+{
+ unsigned int i;
+
+ i = 1024 * (theta % FP16_2PI) / FP16_2PI;
+ switch (i / 256) {
+ case 0:
+ return (fp16_sin_table[i % 256]);
+ case 1:
+ return (fp16_sin_table[255 - i % 256]);
+ case 2:
+ return (-fp16_sin_table[i % 256]);
+ case 3:
+ return (-fp16_sin_table[255 - i % 256]);
+ default:
+ /* inconceivable! */
+ return (0);
+ }
+}
+
+/*
* Compute the cosine of theta.
*/
fp16_t
@@ -117,13 +141,13 @@ fp16_cos(fp16_t theta)
i = 1024 * (theta % FP16_2PI) / FP16_2PI;
switch (i / 256) {
case 0:
- return (fp16_cos_table[i % 256]);
+ return (fp16_sin_table[255 - i % 256]);
case 1:
- return (-fp16_cos_table[255 - i % 256]);
+ return (-fp16_sin_table[i % 256]);
case 2:
- return (-fp16_cos_table[i % 256]);
+ return (-fp16_sin_table[255 - i % 256]);
case 3:
- return (fp16_cos_table[255 - i % 256]);
+ return (fp16_sin_table[i % 256]);
default:
/* inconceivable! */
return (0);
Modified: head/sys/dev/syscons/plasma/fp16.h
==============================================================================
--- head/sys/dev/syscons/plasma/fp16.h Sat Jan 2 10:07:31 2016
(r293048)
+++ head/sys/dev/syscons/plasma/fp16.h Sat Jan 2 16:40:37 2016
(r293049)
@@ -78,7 +78,8 @@ fp16_t fp16_sqrt(fp16_t);
#define FP16_PI_2 102943
#define FP16_PI_4 51471
-/* cosine */
+/* sine and cosine */
+fp16_t fp16_sin(fp16_t);
fp16_t fp16_cos(fp16_t);
#endif
Modified: head/sys/dev/syscons/plasma/plasma_saver.c
==============================================================================
--- head/sys/dev/syscons/plasma/plasma_saver.c Sat Jan 2 10:07:31 2016
(r293048)
+++ head/sys/dev/syscons/plasma/plasma_saver.c Sat Jan 2 16:40:37 2016
(r293049)
@@ -104,7 +104,7 @@ plasma_update(video_adapter_t *adp)
sqd = ItoFP16(dx * dx + dy * dy);
d = fp16_sqrt(sqd);
/* divide by 4 to stretch out the pattern */
- m = fp16_add(m, fp16_cos(d / 4));
+ m = fp16_sub(m, fp16_cos(d / 4));
}
/*
* m is now in the range +/- FOCI, but we need a
_______________________________________________
svn-src-head@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
