Add misc math functions

sqrt_integer.c

+/* Audio Library for Teensy 3.X
+ * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
+ *
+ * Development of this audio library was funded by PJRC.COM, LLC by sales of
+ * Teensy and Audio Adaptor boards.  Please support PJRC's efforts to develop
+ * open source software by purchasing Teensy or other PJRC products.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice, development funding notice, and this permission
+ * notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "sqrt_integer.h"
+
+const uint16_t sqrt_integer_guess_table[33] = {
+55109,
+38968,
+27555,
+19484,
+13778,
+ 9742,
+ 6889,
+ 4871,
+ 3445,
+ 2436,
+ 1723,
+ 1218,
+  862,
+  609,
+  431,
+  305,
+  216,
+  153,
+  108,
+   77,
+   54,
+   39,
+   27,
+   20,
+   14,
+   10,
+    7,
+    5,
+    4,
+    3,
+    2,
+    1,
+    0
+};
+/*
+#! /usr/bin/perl
+use POSIX;
+print "const uint16_t sqrt_integer_guess_table[33] = {\n";
+for ($i=0; $i <= 32; $i++) {
+	printf "%5d", ceil(sqrt((0xFFFFFFFF >> $i) * sqrt(2)/2 ));
+	print "," if $i < 32;
+	print "\n";
+}
+print "};\n";
+*/

sqrt_integer.h

+/* Audio Library for Teensy 3.X
+ * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
+ *
+ * Development of this audio library was funded by PJRC.COM, LLC by sales of
+ * Teensy and Audio Adaptor boards.  Please support PJRC's efforts to develop
+ * open source software by purchasing Teensy or other PJRC products.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice, development funding notice, and this permission
+ * notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" const uint16_t sqrt_integer_guess_table[];
+#else
+extern const uint16_t sqrt_integer_guess_table[];
+#endif
+
+inline uint32_t sqrt_uint32(uint32_t in) __attribute__((always_inline,unused));
+inline uint32_t sqrt_uint32(uint32_t in)
+{
+	uint32_t n = sqrt_integer_guess_table[__builtin_clz(in)];
+	n = ((in / n) + n) / 2;
+	n = ((in / n) + n) / 2;
+	n = ((in / n) + n) / 2;
+	return n;
+}
+
+inline uint32_t sqrt_uint32_approx(uint32_t in) __attribute__((always_inline,unused));
+inline uint32_t sqrt_uint32_approx(uint32_t in)
+{
+	uint32_t n = sqrt_integer_guess_table[__builtin_clz(in)];
+	n = ((in / n) + n) / 2;
+	n = ((in / n) + n) / 2;
+	return n;
+}
+

utility/dspinst.h

 	return a;
 }
 
+// computes ((a[15:0] * b[15:0]) + (a[31:16] * b[31:16]))
+static inline int32_t multiply_16tx16t_add_16bx16b(uint32_t a, uint32_t b) __attribute__((always_inline, unused));
+static inline int32_t multiply_16tx16t_add_16bx16b(uint32_t a, uint32_t b)
+{
+	int32_t out;
+	asm volatile("smuad %0, %1, %2" : "=r" (out) : "r" (a), "r" (b));
+	return out;
+}
+
+// computes ((a[15:0] * b[31:16]) + (a[31:16] * b[15:0]))
+static inline int32_t multiply_16tx16b_add_16bx16t(uint32_t a, uint32_t b) __attribute__((always_inline, unused));
+static inline int32_t multiply_16tx16b_add_16bx16t(uint32_t a, uint32_t b)
+{
+	int32_t out;
+	asm volatile("smuad %0, %1, %2" : "=r" (out) : "r" (a), "r" (b));
+	return out;
+}
+
 #endif