QMath.h File Reference

#include <cassert>
#include <cstdint>

Go to the source code of this file.

Typedefs
template<int N, typename T >
using	V = T __attribute__((ext_vector_type(N)))
using	Q15 = V< 8, uint16_t >
using	I16 = V< 8, int16_t >
using	U16 = V< 8, uint16_t >

Functions
static U16	constrained_add (I16 a, U16 b)
static I16	simulate_ssse3_mm_mulhrs_epi16 (I16 a, I16 b)
static Q15	simulate_neon_vqrdmulhq_s16 (Q15 a, Q15 b)

Typedef Documentation

I16

using I16 = V<8, int16_t>

Definition at line 30 of file QMath.h.

Q15

using Q15 = V<8, uint16_t>

Definition at line 29 of file QMath.h.

U16

using U16 = V<8, uint16_t>

Definition at line 31 of file QMath.h.

V

template<int N, typename T >

using V = T __attribute__((ext_vector_type(N)))

Definition at line 11 of file QMath.h.

Function Documentation

constrained_add()

static U16 constrained_add ( I16  a, U16  b  )

inlinestatic

Definition at line 34 of file QMath.h.

                                                {
for (size_t i = 0; i < 8; i++) {
    // Ensure that a + b is on the interval [0, UINT16_MAX]
    assert(-b[i] <= a[i] && a[i] <= UINT16_MAX - b[i]);
}
    U16 answer = b + a;
    return answer;
}

simulate_neon_vqrdmulhq_s16()

static Q15 simulate_neon_vqrdmulhq_s16 ( Q15  a, Q15  b  )

inlinestatic

Definition at line 58 of file QMath.h.

                                                            {
    Q15 result;
    const int esize = 16;
    auto m = [](int16_t r, int16_t s) {
        const int64_t rounding = 1 << (esize - 1);
        int64_t product = 2LL * (int64_t)r * (int64_t)s + rounding;
        int64_t result = product >> esize;
 
        // Saturate the result
        if (int64_t limit =  (1LL << (esize - 1)) - 1; result > limit) { result = limit; }
        if (int64_t limit = -(1LL << (esize - 1))    ; result < limit) { result = limit; }
        return result;
    };
    for (int i = 0; i < 8; i++) {
        result[i] = m(a[i], b[i]);
    }
    return result;
}

simulate_ssse3_mm_mulhrs_epi16()

static I16 simulate_ssse3_mm_mulhrs_epi16 ( I16  a, I16  b  )

inlinestatic

Definition at line 44 of file QMath.h.

                                                               {
    I16 result;
    auto m = [](int16_t r, int16_t s) {
        const int32_t rounding = 1 << 14;
        int32_t temp = (int32_t)r * (int32_t)s + rounding;
        return (int16_t)(temp >> 15);
    };
    for (int i = 0; i < 8; i++) {
        result[i] = m(a[i], b[i]);
    }
    return result;
}