OpenBLAS/kernel/x86_64/tobf16.c

/***************************************************************************
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#include <stddef.h>
#include "common.h"

#if defined(DOUBLE)
#define FLOAT_TYPE double
#elif defined(SINGLE)
#define FLOAT_TYPE float
#else
#endif

#if defined(COOPERLAKE) || defined(SAPPHIRERAPIDS)
#if defined(DOUBLE)
#include "dtobf16_microk_cooperlake.c"
#elif defined(SINGLE)
#include "stobf16_microk_cooperlake.c"
#endif
#endif

/* Notes for algorithm:
 * - Round to Nearest Even used generally
 * - QNAN for NAN case
 * - Input denormals are treated as zero
 */
static void tobf16_generic_kernel(BLASLONG n, const FLOAT_TYPE * in, BLASLONG inc_in, bfloat16 * out, BLASLONG inc_out)
{
    BLASLONG register index_in  = 0;
    BLASLONG register index_out = 0;
    BLASLONG register index     = 0;
    float             float_in  = 0.0;
    uint32_t *        uint32_in = (uint32_t *)(&float_in);
    uint16_t *        uint16_in = (uint16_t *)(&float_in);

    while(index<n) {
#if defined(DOUBLE)
        float_in = (float)(*(in+index_in));
#else
        float_in = *(in+index_in);
#endif

        switch((*uint32_in) & 0xff800000u) {
            case (0x00000000u):   /* Type 1: Positive denormal */
                *(out+index_out) = 0x0000u;
                break;
            case (0x80000000u):   /* Type 2: Negative denormal */
                *(out+index_out) = 0x8000u;
                break;
            case (0x7f800000u):   /* Type 3: Positive infinity or NAN */
            case (0xff800000u):   /* Type 4: Negative infinity or NAN */
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
                *(out+index_out) = uint16_in[1];
#else
                *(out+index_out) = uint16_in[0];
#endif
                /* Specific for NAN */
                if (((*uint32_in) & 0x007fffffu) != 0) {
                    /* Force to be QNAN */
                    *(out+index_out) |= 0x0040u;
                }
                break;
            default:              /* Type 5: Normal case */
                (*uint32_in) += ((((*uint32_in) >> 16) & 0x1u) + 0x7fffu);
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
                *(out+index_out) = uint16_in[1];
#else
                *(out+index_out) = uint16_in[0];
#endif
                break;
        }

        index_in  += inc_in;
        index_out += inc_out;
        index++;
    }
}

#ifndef HAVE_TOBF16_ACCL_KERNEL
static void tobf16_accl_kernel(BLASLONG n, const FLOAT_TYPE * in, bfloat16 * out)
{
    tobf16_generic_kernel(n, in, 1, out, 1);
}
#endif

static void tobf16_compute(BLASLONG n, FLOAT_TYPE * in, BLASLONG inc_in, bfloat16 * out, BLASLONG inc_out)
{
    if ((inc_in == 1) && (inc_out == 1)) {
        tobf16_accl_kernel(n, in, out);
    } else {
        tobf16_generic_kernel(n, in, inc_in, out, inc_out);
    }
}

#if defined(SMP)
static int tobf16_thread_func(BLASLONG n, BLASLONG dummy0, BLASLONG dummy1, FLOAT_TYPE dummy2,
                            FLOAT_TYPE *x, BLASLONG inc_x, bfloat16 *y, BLASLONG inc_y,
                            FLOAT_TYPE *dummy3, BLASLONG dummy4)
{
        tobf16_compute(n, x, inc_x, y, inc_y);
        return 0;
}

extern int blas_level1_thread(int mode, BLASLONG m, BLASLONG n, BLASLONG k, void *alpha,
                              void *a, BLASLONG lda, void *b, BLASLONG ldb, void *c, BLASLONG ldc,
                              int (*function)(), int nthreads);
#endif

void CNAME(BLASLONG n, FLOAT_TYPE * in, BLASLONG inc_in, bfloat16 * out, BLASLONG inc_out)
{
    if (n <= 0)  return;

#if defined(SMP)
    int nthreads;
    FLOAT_TYPE dummy_alpha;
    FLOAT_TYPE dummy_c;
#endif

#if defined(SMP)
    if (inc_in == 0 || inc_out == 0 || n <= 100000) {
        nthreads = 1;
    } else {
        nthreads = num_cpu_avail(1);
        if (n/100000 < 100) {
            nthreads = MAX(nthreads,4);
//        } else {
//            nthreads = MAX(nthreads,16);
        }
    }

    if (nthreads == 1) {
        tobf16_compute(n, in, inc_in, out, inc_out);
    } else {
#if defined(DOUBLE)
        int mode = BLAS_REAL | BLAS_DTOBF16;
#elif defined(SINGLE)
        int mode = BLAS_REAL | BLAS_STOBF16;
#endif
        blas_level1_thread(mode, n, 0, 0, &dummy_alpha,
                           in, inc_in, out, inc_out, &dummy_c, 0,
                           (void *)tobf16_thread_func, nthreads);
    }
#else
    tobf16_compute(n, in, inc_in, out, inc_out);
#endif

}