AP_Math: Move conversion utilites next to AP_Math

* This is next to the constraining functions

Signed-off-by: Ryan Friedman <ryanfriedman5410+github@gmail.com>

libraries/AP_Math/AP_Math.cpp

@@ -526,3 +526,40 @@ int32_t double_to_int32(const double v)
 {
     return int32_t(constrain_double(v, INT32_MIN, UINT32_MAX));
 }
+
+
+int32_t float_to_int32_le(const float& value)
+{
+    int32_t out;
+    static_assert(sizeof(value) == sizeof(out));
+
+    // Use memcpy because it's the most portable.
+    // It might not be the fastest way on all hardware.
+    // At least it's defined behavior in both c and c++.
+    memcpy(&out, &value, sizeof(out));
+    return out;
+}
+
+float int32_to_float_le(const uint32_t& value)
+{
+    float out;
+    static_assert(sizeof(value) == sizeof(out));
+
+    // Use memcpy because it's the most portable.
+    // It might not be the fastest way on all hardware.
+    // At least it's defined behavior in both c and c++.
+    memcpy(&out, &value, sizeof(out));
+    return out;
+}
+
+double uint64_to_double_le(const uint64_t& value)
+{
+    double out;
+    static_assert(sizeof(value) == sizeof(out));
+
+    // Use memcpy because it's the most portable.
+    // It might not be the fastest way on all hardware.
+    // At least it's defined behavior in both c and c++.
+    memcpy(&out, &value, sizeof(out));
+    return out;
+}

libraries/AP_Math/AP_Math.h

@@ -366,7 +366,7 @@ float fixedwing_turn_rate(float bank_angle_deg, float airspeed);
 float degF_to_Kelvin(float temp_f);
 
 /*
-  conversion functions to prevent undefined behaviour
+  constraining conversion functions to prevent undefined behaviour
  */
 int16_t float_to_int16(const float v);
 uint16_t float_to_uint16(const float v);
@@ -375,3 +375,17 @@ uint32_t float_to_uint32(const float v);
 uint32_t double_to_uint32(const double v);
 int32_t double_to_int32(const double v);
 
+/*
+  Convert from float to int32_t without breaking Wstrict-aliasing due to type punning
+*/
+int32_t float_to_int32_le(const float& value) WARN_IF_UNUSED;
+
+/*
+  Convert from uint32_t to float without breaking Wstrict-aliasing due to type punning
+*/
+float int32_to_float_le(const uint32_t& value) WARN_IF_UNUSED;
+
+/*
+  Convert from uint64_t to double without breaking Wstrict-aliasing due to type punning
+*/
+double uint64_to_double_le(const uint64_t& value) WARN_IF_UNUSED;