Date: Sat, 2 Jan 2016 16:40:37 +0000 (UTC) From: =?UTF-8?Q?Dag-Erling_Sm=c3=b8rgrav?= <des@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r293049 - head/sys/dev/syscons/plasma Message-ID: <201601021640.u02GebdU030988@repo.freebsd.org>
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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
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