qemu-e2k/target/hexagon/arch.c

/*
 *  Copyright(c) 2019-2021 Qualcomm Innovation Center, Inc. All Rights Reserved.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include "qemu/osdep.h"
#include "fpu/softfloat.h"
#include "cpu.h"
#include "fma_emu.h"
#include "arch.h"
#include "macros.h"

#define SF_BIAS        127
#define SF_MAXEXP      254
#define SF_MANTBITS    23
#define float32_nan    make_float32(0xffffffff)

#define BITS_MASK_8 0x5555555555555555ULL
#define PAIR_MASK_8 0x3333333333333333ULL
#define NYBL_MASK_8 0x0f0f0f0f0f0f0f0fULL
#define BYTE_MASK_8 0x00ff00ff00ff00ffULL
#define HALF_MASK_8 0x0000ffff0000ffffULL
#define WORD_MASK_8 0x00000000ffffffffULL

uint64_t interleave(uint32_t odd, uint32_t even)
{
    /* Convert to long long */
    uint64_t myodd = odd;
    uint64_t myeven = even;
    /* First, spread bits out */
    myodd = (myodd | (myodd << 16)) & HALF_MASK_8;
    myeven = (myeven | (myeven << 16)) & HALF_MASK_8;
    myodd = (myodd | (myodd << 8)) & BYTE_MASK_8;
    myeven = (myeven | (myeven << 8)) & BYTE_MASK_8;
    myodd = (myodd | (myodd << 4)) & NYBL_MASK_8;
    myeven = (myeven | (myeven << 4)) & NYBL_MASK_8;
    myodd = (myodd | (myodd << 2)) & PAIR_MASK_8;
    myeven = (myeven | (myeven << 2)) & PAIR_MASK_8;
    myodd = (myodd | (myodd << 1)) & BITS_MASK_8;
    myeven = (myeven | (myeven << 1)) & BITS_MASK_8;
    /* Now OR together */
    return myeven | (myodd << 1);
}

uint64_t deinterleave(uint64_t src)
{
    /* Get odd and even bits */
    uint64_t myodd = ((src >> 1) & BITS_MASK_8);
    uint64_t myeven = (src & BITS_MASK_8);

    /* Unspread bits */
    myeven = (myeven | (myeven >> 1)) & PAIR_MASK_8;
    myodd = (myodd | (myodd >> 1)) & PAIR_MASK_8;
    myeven = (myeven | (myeven >> 2)) & NYBL_MASK_8;
    myodd = (myodd | (myodd >> 2)) & NYBL_MASK_8;
    myeven = (myeven | (myeven >> 4)) & BYTE_MASK_8;
    myodd = (myodd | (myodd >> 4)) & BYTE_MASK_8;
    myeven = (myeven | (myeven >> 8)) & HALF_MASK_8;
    myodd = (myodd | (myodd >> 8)) & HALF_MASK_8;
    myeven = (myeven | (myeven >> 16)) & WORD_MASK_8;
    myodd = (myodd | (myodd >> 16)) & WORD_MASK_8;

    /* Return odd bits in upper half */
    return myeven | (myodd << 32);
}

int32_t conv_round(int32_t a, int n)
{
    int64_t val;

    if (n == 0) {
        val = a;
    } else if ((a & ((1 << (n - 1)) - 1)) == 0) {    /* N-1..0 all zero? */
        /* Add LSB from int part */
        val = ((fSE32_64(a)) + (int64_t) (((uint32_t) ((1 << n) & a)) >> 1));
    } else {
        val = ((fSE32_64(a)) + (1 << (n - 1)));
    }

    val = val >> n;
    return (int32_t)val;
}

/* Floating Point Stuff */

static const FloatRoundMode softfloat_roundingmodes[] = {
    float_round_nearest_even,
    float_round_to_zero,
    float_round_down,
    float_round_up,
};

void arch_fpop_start(CPUHexagonState *env)
{
    set_float_exception_flags(0, &env->fp_status);
    set_float_rounding_mode(
        softfloat_roundingmodes[fREAD_REG_FIELD(USR, USR_FPRND)],
        &env->fp_status);
}

#ifdef CONFIG_USER_ONLY
/*
 * Hexagon Linux kernel only sets the relevant bits in USR (user status
 * register).  The exception isn't raised to user mode, so we don't
 * model it in qemu user mode.
 */
#define RAISE_FP_EXCEPTION   do {} while (0)
#endif

#define SOFTFLOAT_TEST_FLAG(FLAG, MYF, MYE) \
    do { \
        if (flags & FLAG) { \
            if (GET_USR_FIELD(USR_##MYF) == 0) { \
                SET_USR_FIELD(USR_##MYF, 1); \
                if (GET_USR_FIELD(USR_##MYE)) { \
                    RAISE_FP_EXCEPTION; \
                } \
            } \
        } \
    } while (0)

void arch_fpop_end(CPUHexagonState *env)
{
    int flags = get_float_exception_flags(&env->fp_status);
    if (flags != 0) {
        SOFTFLOAT_TEST_FLAG(float_flag_inexact, FPINPF, FPINPE);
        SOFTFLOAT_TEST_FLAG(float_flag_divbyzero, FPDBZF, FPDBZE);
        SOFTFLOAT_TEST_FLAG(float_flag_invalid, FPINVF, FPINVE);
        SOFTFLOAT_TEST_FLAG(float_flag_overflow, FPOVFF, FPOVFE);
        SOFTFLOAT_TEST_FLAG(float_flag_underflow, FPUNFF, FPUNFE);
    }
}

int arch_sf_recip_common(float32 *Rs, float32 *Rt, float32 *Rd, int *adjust,
                         float_status *fp_status)
{
    int n_exp;
    int d_exp;
    int ret = 0;
    float32 RsV, RtV, RdV;
    int PeV = 0;
    RsV = *Rs;
    RtV = *Rt;
    if (float32_is_any_nan(RsV) && float32_is_any_nan(RtV)) {
        if (extract32(RsV & RtV, 22, 1) == 0) {
            float_raise(float_flag_invalid, fp_status);
        }
        RdV = RsV = RtV = float32_nan;
    } else if (float32_is_any_nan(RsV)) {
        if (extract32(RsV, 22, 1) == 0) {
            float_raise(float_flag_invalid, fp_status);
        }
        RdV = RsV = RtV = float32_nan;
    } else if (float32_is_any_nan(RtV)) {
        /* or put NaN in num/den fixup? */
        if (extract32(RtV, 22, 1) == 0) {
            float_raise(float_flag_invalid, fp_status);
        }
        RdV = RsV = RtV = float32_nan;
    } else if (float32_is_infinity(RsV) && float32_is_infinity(RtV)) {
        /* or put Inf in num fixup? */
        RdV = RsV = RtV = float32_nan;
        float_raise(float_flag_invalid, fp_status);
    } else if (float32_is_zero(RsV) && float32_is_zero(RtV)) {
        /* or put zero in num fixup? */
        RdV = RsV = RtV = float32_nan;
        float_raise(float_flag_invalid, fp_status);
    } else if (float32_is_zero(RtV)) {
        /* or put Inf in num fixup? */
        uint8_t RsV_sign = float32_is_neg(RsV);
        uint8_t RtV_sign = float32_is_neg(RtV);
        RsV = infinite_float32(RsV_sign ^ RtV_sign);
        RtV = float32_one;
        RdV = float32_one;
        if (float32_is_infinity(RsV)) {
            float_raise(float_flag_divbyzero, fp_status);
        }
    } else if (float32_is_infinity(RtV)) {
        RsV = make_float32(0x80000000 & (RsV ^ RtV));
        RtV = float32_one;
        RdV = float32_one;
    } else if (float32_is_zero(RsV)) {
        /* Does this just work itself out? */
        /* No, 0/Inf causes problems. */
        RsV = make_float32(0x80000000 & (RsV ^ RtV));
        RtV = float32_one;
        RdV = float32_one;
    } else if (float32_is_infinity(RsV)) {
        uint8_t RsV_sign = float32_is_neg(RsV);
        uint8_t RtV_sign = float32_is_neg(RtV);
        RsV = infinite_float32(RsV_sign ^ RtV_sign);
        RtV = float32_one;
        RdV = float32_one;
    } else {
        PeV = 0x00;
        /* Basic checks passed */
        n_exp = float32_getexp(RsV);
        d_exp = float32_getexp(RtV);
        if ((n_exp - d_exp + SF_BIAS) <= SF_MANTBITS) {
            /* Near quotient underflow / inexact Q */
            PeV = 0x80;
            RtV = float32_scalbn(RtV, -64, fp_status);
            RsV = float32_scalbn(RsV, 64, fp_status);
        } else if ((n_exp - d_exp + SF_BIAS) > (SF_MAXEXP - 24)) {
            /* Near quotient overflow */
            PeV = 0x40;
            RtV = float32_scalbn(RtV, 32, fp_status);
            RsV = float32_scalbn(RsV, -32, fp_status);
        } else if (n_exp <= SF_MANTBITS + 2) {
            RtV = float32_scalbn(RtV, 64, fp_status);
            RsV = float32_scalbn(RsV, 64, fp_status);
        } else if (d_exp <= 1) {
            RtV = float32_scalbn(RtV, 32, fp_status);
            RsV = float32_scalbn(RsV, 32, fp_status);
        } else if (d_exp > 252) {
            RtV = float32_scalbn(RtV, -32, fp_status);
            RsV = float32_scalbn(RsV, -32, fp_status);
        }
        RdV = 0;
        ret = 1;
    }
    *Rs = RsV;
    *Rt = RtV;
    *Rd = RdV;
    *adjust = PeV;
    return ret;
}

int arch_sf_invsqrt_common(float32 *Rs, float32 *Rd, int *adjust,
                           float_status *fp_status)
{
    float32 RsV, RdV;
    int PeV = 0;
    int r_exp;
    int ret = 0;
    RsV = *Rs;
    if (float32_is_infinity(RsV)) {
        if (extract32(RsV, 22, 1) == 0) {
            float_raise(float_flag_invalid, fp_status);
        }
        RdV = RsV = float32_nan;
    } else if (float32_lt(RsV, float32_zero, fp_status)) {
        /* Negative nonzero values are NaN */
        float_raise(float_flag_invalid, fp_status);
        RsV = float32_nan;
        RdV = float32_nan;
    } else if (float32_is_infinity(RsV)) {
        /* or put Inf in num fixup? */
        RsV = infinite_float32(1);
        RdV = infinite_float32(1);
    } else if (float32_is_zero(RsV)) {
        /* or put zero in num fixup? */
        RdV = float32_one;
    } else {
        PeV = 0x00;
        /* Basic checks passed */
        r_exp = float32_getexp(RsV);
        if (r_exp <= 24) {
            RsV = float32_scalbn(RsV, 64, fp_status);
            PeV = 0xe0;
        }
        RdV = 0;
        ret = 1;
    }
    *Rs = RsV;
    *Rd = RdV;
    *adjust = PeV;
    return ret;
}