From d75b6ad8892f71f4ea69dfda865cc11e5afa7834 Mon Sep 17 00:00:00 2001
From: Stephan Hadinger <stephan.hadinger@gmail.com>
Date: Mon, 1 Jul 2019 18:31:54 +0200
Subject: [PATCH] Moved FastPrecisePow and TaylorLog to sonoff_float.ino for
 consistency

---
 sonoff/support.ino       | 60 ---------------------------------------
 sonoff/support_float.ino | 61 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 60 deletions(-)

diff --git a/sonoff/support.ino b/sonoff/support.ino
index ba0a7bbad..41e5ffd3b 100644
--- a/sonoff/support.ino
+++ b/sonoff/support.ino
@@ -650,66 +650,6 @@ void ResetGlobalValues(void)
   }
 }
 
-double FastPrecisePow(double a, double b)
-{
-  // https://martin.ankerl.com/2012/01/25/optimized-approximative-pow-in-c-and-cpp/
-  // calculate approximation with fraction of the exponent
-  int e = abs((int)b);
-  union {
-    double d;
-    int x[2];
-  } u = { a };
-  u.x[1] = (int)((b - e) * (u.x[1] - 1072632447) + 1072632447);
-  u.x[0] = 0;
-  // exponentiation by squaring with the exponent's integer part
-  // double r = u.d makes everything much slower, not sure why
-  double r = 1.0;
-  while (e) {
-    if (e & 1) {
-      r *= a;
-    }
-    a *= a;
-    e >>= 1;
-  }
-  return r * u.d;
-}
-
-float FastPrecisePowf(const float x, const float y)
-{
-//  return (float)(pow((double)x, (double)y));
-  return (float)FastPrecisePow(x, y);
-}
-
-double TaylorLog(double x)
-{
-  // https://stackoverflow.com/questions/46879166/finding-the-natural-logarithm-of-a-number-using-taylor-series-in-c
-
-  if (x <= 0.0) { return NAN; }
-  double z = (x + 1) / (x - 1);                              // We start from power -1, to make sure we get the right power in each iteration;
-  double step = ((x - 1) * (x - 1)) / ((x + 1) * (x + 1));   // Store step to not have to calculate it each time
-  double totalValue = 0;
-  double powe = 1;
-  double y;
-  for (uint32_t count = 0; count < 10; count++) {                 // Experimental number of 10 iterations
-    z *= step;
-    y = (1 / powe) * z;
-    totalValue = totalValue + y;
-    powe = powe + 2;
-  }
-  totalValue *= 2;
-/*
-  char logxs[33];
-  dtostrfd(x, 8, logxs);
-  double log1 = log(x);
-  char log1s[33];
-  dtostrfd(log1, 8, log1s);
-  char log2s[33];
-  dtostrfd(totalValue, 8, log2s);
-  AddLog_P2(LOG_LEVEL_DEBUG, PSTR("input %s, log %s, taylor %s"), logxs, log1s, log2s);
-*/
-  return totalValue;
-}
-
 uint32_t SqrtInt(uint32_t num)
 {
   if (num <= 1) {
diff --git a/sonoff/support_float.ino b/sonoff/support_float.ino
index e7b7e62d6..fc2dccf04 100644
--- a/sonoff/support_float.ino
+++ b/sonoff/support_float.ino
@@ -17,6 +17,66 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+double FastPrecisePow(double a, double b)
+{
+  // https://martin.ankerl.com/2012/01/25/optimized-approximative-pow-in-c-and-cpp/
+  // calculate approximation with fraction of the exponent
+  int e = abs((int)b);
+  union {
+    double d;
+    int x[2];
+  } u = { a };
+  u.x[1] = (int)((b - e) * (u.x[1] - 1072632447) + 1072632447);
+  u.x[0] = 0;
+  // exponentiation by squaring with the exponent's integer part
+  // double r = u.d makes everything much slower, not sure why
+  double r = 1.0;
+  while (e) {
+    if (e & 1) {
+      r *= a;
+    }
+    a *= a;
+    e >>= 1;
+  }
+  return r * u.d;
+}
+
+float FastPrecisePowf(const float x, const float y)
+{
+//  return (float)(pow((double)x, (double)y));
+  return (float)FastPrecisePow(x, y);
+}
+
+double TaylorLog(double x)
+{
+  // https://stackoverflow.com/questions/46879166/finding-the-natural-logarithm-of-a-number-using-taylor-series-in-c
+
+  if (x <= 0.0) { return NAN; }
+  double z = (x + 1) / (x - 1);                              // We start from power -1, to make sure we get the right power in each iteration;
+  double step = ((x - 1) * (x - 1)) / ((x + 1) * (x + 1));   // Store step to not have to calculate it each time
+  double totalValue = 0;
+  double powe = 1;
+  double y;
+  for (uint32_t count = 0; count < 10; count++) {                 // Experimental number of 10 iterations
+    z *= step;
+    y = (1 / powe) * z;
+    totalValue = totalValue + y;
+    powe = powe + 2;
+  }
+  totalValue *= 2;
+/*
+  char logxs[33];
+  dtostrfd(x, 8, logxs);
+  double log1 = log(x);
+  char log1s[33];
+  dtostrfd(log1, 8, log1s);
+  char log2s[33];
+  dtostrfd(totalValue, 8, log2s);
+  AddLog_P2(LOG_LEVEL_DEBUG, PSTR("input %s, log %s, taylor %s"), logxs, log1s, log2s);
+*/
+  return totalValue;
+}
+
 // All code adapted from: http://www.ganssle.com/approx.htm
 
 /// ========================================
@@ -32,6 +92,7 @@ inline float atanf(float x) { return atan_66(x); }
 inline float asinf(float x) { return asinf1(x); }
 inline float acosf(float x) { return acosf1(x); }
 inline float sqrtf(float x) { return sqrt1(x); }
+inline float powf(float x, float y) { return FastPrecisePow(x, y); }
 
 // Math constants we'll use
 double const f_pi=3.1415926535897932384626433;	// f_pi