CMSIS-DSP: Correction for issue #1130

Better control of the f16 build.

Include/arm_math.h

@@ -161,7 +161,9 @@
    * - DISABLEFLOAT16:
    *
    * Disable float16 algorithms when __fp16 is not supported for a
-   * specific compiler / core configuration
+   * specific compiler / core configuration.
+   * This is only valid for scalar. When vector architecture is
+   * supporting f16 then it can't be disabled.
    *
    * <hr>
    * \section pack CMSIS-DSP in ARM::CMSIS Pack

Include/arm_math_types_f16.h

@@ -49,15 +49,15 @@ won't be built.
 
 */
 #if !(__ARM_FEATURE_MVE & 2)
-  #if defined(__ARM_FP16_FORMAT_IEEE) || defined(__ARM_FP16_FORMAT_ALTERNATIVE)
-  typedef __fp16 float16_t;
-  #define ARM_FLOAT16_SUPPORTED
-  #endif
-#else
-  /* HW Float16 not yet well supported on some configs */
   #if !defined(DISABLEFLOAT16)
-    #define ARM_FLOAT16_SUPPORTED
+    #if defined(__ARM_FP16_FORMAT_IEEE) || defined(__ARM_FP16_FORMAT_ALTERNATIVE)
+      typedef __fp16 float16_t;
+      #define ARM_FLOAT16_SUPPORTED
+    #endif
   #endif
+#else
+  /* When Vector float16, this flag is always defined and can't be disabled */
+  #define ARM_FLOAT16_SUPPORTED
 #endif
 
 #if defined(ARM_MATH_NEON) || (defined(ARM_MATH_MVEF)  && !defined(ARM_MATH_AUTOVECTORIZE)) /* floating point vector*/

Source/TransformFunctions/arm_cfft_radix2_init_f16.c

@@ -63,6 +63,8 @@
                    This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
 */
 
+#if defined(ARM_FLOAT16_SUPPORTED)
+
 arm_status arm_cfft_radix2_init_f16(
   arm_cfft_radix2_instance_f16 * S,
   uint16_t fftLen,
@@ -203,6 +205,7 @@ arm_status arm_cfft_radix2_init_f16(
   return (status);
 }
 
+#endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
 /**
   @} end of ComplexFFT group
  */

Source/TransformFunctions/arm_cfft_radix4_init_f16.c

@@ -66,6 +66,8 @@
                    This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
  */
 
+#if defined(ARM_FLOAT16_SUPPORTED)
+
 arm_status arm_cfft_radix4_init_f16(
   arm_cfft_radix4_instance_f16 * S,
   uint16_t fftLen,
@@ -163,7 +165,7 @@ arm_status arm_cfft_radix4_init_f16(
 #endif
   return (status);
 }
-
+#endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
 /**
   @} end of ComplexFFT group
  */