Function arm_nn_activation_f32

Function Documentation

arm_cmsis_nn_status arm_nn_activation_f32(const float32_t *input, float32_t *output, int32_t size, arm_nn_activation_type_flt type, float32_t act_param)

Elementwise activation.

Note

The RELU, RELU6 and LEAKY_RELU legs classify NaN on the integer bit pattern (#380 / #382), so a NaN input comes back as NaN at every optimization level on the gated toolchains, including the shipped -Ofast. This holds on both the scalar and the MVE (cortex-m55) build paths; the MVE RELU/RELU6 legs restore the NaN lanes that vmaxnmq/vminnmq suppress. SIGMOID, TANH and HARDSWISH are outside this contract; see the per-helper notes in Include/Internal/arm_nn_activation_flt.h.

Note

The HARDSWISH leg’s scalar helper (arm_nn_hardswish_scalar_f32, serving every build that does not take the MVE float path — no MVE float support, or MVE present but not used, e.g. under ARM_MATH_AUTOVECTORIZE) keeps the legacy separately rounded multiply-and-add gate and can differ by an ulp in the curved region from the standalone arm_hard_swish_f32, whose gate is a correctly rounded fma; the mux’s MVE helper (arm_nn_vhardswish_mve_f32) uses vfmaq and agrees with that kernel. Callers that need bit-exact, leg-agreeing hard swish — or the documented NaN/Inf contract — should call arm_hard_swish_f32 directly.

Parameters:

  • input – [in] Pointer to the input samples.

  • output – [out] Pointer to the output samples.

  • size – [in] Number of elements to process.

  • type – [in] Activation selector.

  • act_param – [in] Extra activation parameter. Used for parameterized activations such as leaky ReLU.

Returns:

ARM_CMSIS_NN_SUCCESS on success or ARM_CMSIS_NN_ARG_ERROR on invalid arguments.