Commit ca2dde7f8d795b2d6f42a7db07f16409e56ac272
2023-05-18T22:05:40
wip sin
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diff --git a/math/sin.c b/math/sin.c
new file mode 100644
index 0000000..37088a8
--- /dev/null
+++ b/math/sin.c
@@ -0,0 +1,46 @@
+/* c3
+ * Copyright 2022,2023 kmx.io <contact@kmx.io>
+ *
+ * Permission is hereby granted to use this software granted the above
+ * copyright notice and this permission paragraph are included in all
+ * copies and substantial portions of this software.
+ *
+ * THIS SOFTWARE IS PROVIDED "AS-IS" WITHOUT ANY GUARANTEE OF
+ * PURPOSE AND PERFORMANCE. IN NO EVENT WHATSOEVER SHALL THE
+ * AUTHOR BE CONSIDERED LIABLE FOR THE USE AND PERFORMANCE OF
+ * THIS SOFTWARE.
+ */
+#include "sin.h"
+
+s8 sin_u8 (u8 x)
+{
+ s16 i;
+ u8 n;
+ u8 side_bits;
+ s8 y;
+ side_bits = (sizeof(u8) * 8 - 3);
+ n = (1 << side_bits) - 1;
+ switch (x >> side_bits) {
+ case 0:
+ i = x & n;
+ y = (S16_MAX) i * S8_MAX / n * S8_MAX / sqrt(n * n + i * i / n / n) / S8_MAX;
+ return y;
+ case 1:
+ return 1;
+ case 2:
+ return 2;
+ case 3:
+ return 3;
+ case 4:
+ return 4;
+ case 5:
+ return 5;
+ case 6:
+ return 6;
+ case 7:
+ return 7;
+ }
+ assert(! "sin_u8: error");
+ errx(1, "sin_u8");
+ return 0;
+}
diff --git a/math/sin.h b/math/sin.h
new file mode 100644
index 0000000..84fa012
--- /dev/null
+++ b/math/sin.h
@@ -0,0 +1,20 @@
+/* c3
+ * Copyright 2022,2023 kmx.io <contact@kmx.io>
+ *
+ * Permission is hereby granted to use this software granted the above
+ * copyright notice and this permission paragraph are included in all
+ * copies and substantial portions of this software.
+ *
+ * THIS SOFTWARE IS PROVIDED "AS-IS" WITHOUT ANY GUARANTEE OF
+ * PURPOSE AND PERFORMANCE. IN NO EVENT WHATSOEVER SHALL THE
+ * AUTHOR BE CONSIDERED LIABLE FOR THE USE AND PERFORMANCE OF
+ * THIS SOFTWARE.
+ */
+#ifndef SIN_H
+#define SIN_H
+
+#include "types.h"
+
+s8 sin_s8 (s8 x);
+
+#endif /* SIN_H */