IVGCVSW-2721 Quantize and Dequantize aren't quite right

 * Add check for infinity and negative infinity in quantize()
 * Add assert for NaN value in quantize and dequantize()
 * Add unit tests for infinity and negative infinity

Change-Id: Ie60e1e15b289ccbf99df4a3281f067b82cc9f9bf
Signed-off-by: Francis Murtagh <francis.murtagh@arm.com>

1 files changed, 7 insertions, 8 deletions

diff --git a/include/armnn/TypesUtils.hpp b/include/armnn/TypesUtils.hpp
index c65eefc510..e7652649b0 100644
--- a/include/armnn/TypesUtils.hpp
+++ b/include/armnn/TypesUtils.hpp
@@ -189,18 +189,16 @@ inline std::ostream & operator<<(std::ostream & os, const armnn::TensorShape & s
 template<typename QuantizedType>
 inline QuantizedType Quantize(float value, float scale, int32_t offset)
 {
-    // TODO : check we act sensibly for Inf, NaN and -Inf
-    //        see IVGCVSW-1849
     static_assert(IsQuantizedType<QuantizedType>(), "Not an integer type.");
     constexpr QuantizedType max = std::numeric_limits<QuantizedType>::max();
     constexpr QuantizedType min = std::numeric_limits<QuantizedType>::lowest();
     BOOST_ASSERT(scale != 0.f);
-    int quantized = boost::numeric_cast<int>(round(value / scale)) + offset;
-    QuantizedType quantizedBits = quantized <= min
-                                  ? min
-                                  : quantized >= max
-                                    ? max
-                                    : static_cast<QuantizedType>(quantized);
+    BOOST_ASSERT(!std::isnan(value));
+
+    float clampedValue = std::min(std::max(static_cast<float>(round(value/scale) + offset), static_cast<float>(min)),
+                                  static_cast<float>(max));
+    auto quantizedBits = static_cast<QuantizedType>(clampedValue);
+
     return quantizedBits;
 }
 
@@ -215,6 +213,7 @@ inline float Dequantize(QuantizedType value, float scale, int32_t offset)
 {
     static_assert(IsQuantizedType<QuantizedType>(), "Not an integer type.");
     BOOST_ASSERT(scale != 0.f);
+    BOOST_ASSERT(!std::isnan(value));
     float dequantized = boost::numeric_cast<float>(value - offset) * scale;
     return dequantized;
 }