How to use the multiply and accumulate intrinsics in ARM Cortex-a8?

Question

how to use the Multiply-Accumulate intrinsics provided by GCC?

float32x4_t vmlaq_f32 (float32x4_t , float32x4_t , float32x4_t);

Can anyone expl

Answer 1

Google'd for vmlaq_f32, turned up the reference for the RVCT compiler tools. Here's what it says:

Vector multiply accumulate: vmla -> Vr[i] := Va[i] + Vb[i] * Vc[i]
...
float32x4_t vmlaq_f32 (float32x4_t a, float32x4_t b, float32x4_t c);

AND

The following types are defined to represent vectors. NEON vector data types are named according to the following pattern: x_t For example, int16x4_t is a vector containing four lanes each containing a signed 16-bit integer. Table E.1 lists the vector data types.

IOW, the return value from the function will be a vector containing 4 32-bit floats, and each element of the vector is calculated by multiplying the corresponding elements of b and c, and adding the contents of a.

HTH