COMPMID-2372: Add support for QASYMM8 for Tanh

-Perform calculations in the floating point domain
-Extends checks for Logistic as scale should be 1/256 and offset 0

Change-Id: I90ef4a042f053976936f5d28f8e09b54eec196a2
Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-on: https://review.mlplatform.org/c/1287
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michalis Spyrou <michalis.spyrou@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>

1 files changed, 98 insertions, 0 deletions

diff --git a/arm_compute/core/utils/helpers/float_ops.h b/arm_compute/core/utils/helpers/float_ops.h
new file mode 100644
index 0000000000..5012c8ef84
--- /dev/null
+++ b/arm_compute/core/utils/helpers/float_ops.h
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2019 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * 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 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.
+ */
+#ifndef __ARM_COMPUTE_UTILS_HELPERS_FLOAT_OPS_H__
+#define __ARM_COMPUTE_UTILS_HELPERS_FLOAT_OPS_H__
+
+namespace arm_compute
+{
+namespace helpers
+{
+namespace float_ops
+{
+union RawFloat
+{
+    /** Constructor
+     *
+     * @param[in] val Floating-point value
+     */
+    explicit RawFloat(float val)
+        : f32(val)
+    {
+    }
+    /** Extract sign of floating point number
+     *
+     * @return Sign of floating point number
+     */
+    int32_t sign() const
+    {
+        return i32 >> 31;
+    }
+    /** Extract exponent of floating point number
+     *
+     * @return Exponent of floating point number
+     */
+    int32_t exponent() const
+    {
+        return (i32 >> 23) & 0xFF;
+    }
+    /** Extract mantissa of floating point number
+     *
+     * @return Mantissa of floating point number
+     */
+    int32_t mantissa() const
+    {
+        return i32 & 0x007FFFFF;
+    }
+
+    int32_t i32;
+    float   f32;
+};
+
+/** Checks if two floating point numbers are equal given an allowed number of ULPs
+ *
+ * @param[in] a                First number to compare
+ * @param[in] b                Second number to compare
+ * @param[in] max_allowed_ulps Number of allowed ULPs
+ *
+ * @return True if number is close else false
+ */
+bool is_equal_ulps(float a, float b, int max_allowed_ulps = 0)
+{
+    RawFloat ra(a);
+    RawFloat rb(b);
+
+    // Early check for sign
+    if(ra.sign() != rb.sign())
+    {
+        return (a == b);
+    }
+
+    // Check ULP distance
+    const int ulps = std::abs(ra.i32 - rb.i32);
+    return ulps <= max_allowed_ulps;
+}
+} // namespace float_ops
+} // namespace helpers
+} // namespace arm_compute
+#endif /* __ARM_COMPUTE_UTILS_HELPERS_FLOAT_OPS_H__ */