target-arm/helper-a64.c

/*
 *  AArch64 specific helpers
 *
 *  Copyright (c) 2013 Alexander Graf <agraf@suse.de>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */

#include "cpu.h"
#include "exec/gdbstub.h"
#include "helper.h"
#include "qemu/host-utils.h"
#include "sysemu/sysemu.h"
#include "qemu/bitops.h"

/* C2.4.7 Multiply and divide */
/* special cases for 0 and LLONG_MIN are mandated by the standard */
uint64_t HELPER(udiv64)(uint64_t num, uint64_t den)
{
    if (den == 0) {
        return 0;
    }
    return num / den;
}

int64_t HELPER(sdiv64)(int64_t num, int64_t den)
{
    if (den == 0) {
        return 0;
    }
    if (num == LLONG_MIN && den == -1) {
        return LLONG_MIN;
    }
    return num / den;
}

uint64_t HELPER(clz64)(uint64_t x)
{
    return clz64(x);
}

uint64_t HELPER(cls64)(uint64_t x)
{
    return clrsb64(x);
}

uint32_t HELPER(cls32)(uint32_t x)
{
    return clrsb32(x);
}

uint32_t HELPER(clz32)(uint32_t x)
{
    return clz32(x);
}

uint64_t HELPER(rbit64)(uint64_t x)
{
    /* assign the correct byte position */
    x = bswap64(x);

    /* assign the correct nibble position */
    x = ((x & 0xf0f0f0f0f0f0f0f0ULL) >> 4)
        | ((x & 0x0f0f0f0f0f0f0f0fULL) << 4);

    /* assign the correct bit position */
    x = ((x & 0x8888888888888888ULL) >> 3)
        | ((x & 0x4444444444444444ULL) >> 1)
        | ((x & 0x2222222222222222ULL) << 1)
        | ((x & 0x1111111111111111ULL) << 3);

    return x;
}

/* Convert a softfloat float_relation_ (as returned by
 * the float*_compare functions) to the correct ARM
 * NZCV flag state.
 */
static inline uint32_t float_rel_to_flags(int res)
{
    uint64_t flags;
    switch (res) {
    case float_relation_equal:
        flags = PSTATE_Z | PSTATE_C;
        break;
    case float_relation_less:
        flags = PSTATE_N;
        break;
    case float_relation_greater:
        flags = PSTATE_C;
        break;
    case float_relation_unordered:
    default:
        flags = PSTATE_C | PSTATE_V;
        break;
    }
    return flags;
}

uint64_t HELPER(vfp_cmps_a64)(float32 x, float32 y, void *fp_status)
{
    return float_rel_to_flags(float32_compare_quiet(x, y, fp_status));
}

uint64_t HELPER(vfp_cmpes_a64)(float32 x, float32 y, void *fp_status)
{
    return float_rel_to_flags(float32_compare(x, y, fp_status));
}

uint64_t HELPER(vfp_cmpd_a64)(float64 x, float64 y, void *fp_status)
{
    return float_rel_to_flags(float64_compare_quiet(x, y, fp_status));
}

uint64_t HELPER(vfp_cmped_a64)(float64 x, float64 y, void *fp_status)
{
    return float_rel_to_flags(float64_compare(x, y, fp_status));
}

float32 HELPER(vfp_mulxs)(float32 a, float32 b, void *fpstp)
{
    float_status *fpst = fpstp;

    if ((float32_is_zero(a) && float32_is_infinity(b)) ||
        (float32_is_infinity(a) && float32_is_zero(b))) {
        /* 2.0 with the sign bit set to sign(A) XOR sign(B) */
        return make_float32((1U << 30) |
                            ((float32_val(a) ^ float32_val(b)) & (1U << 31)));
    }
    return float32_mul(a, b, fpst);
}

float64 HELPER(vfp_mulxd)(float64 a, float64 b, void *fpstp)
{
    float_status *fpst = fpstp;

    if ((float64_is_zero(a) && float64_is_infinity(b)) ||
        (float64_is_infinity(a) && float64_is_zero(b))) {
        /* 2.0 with the sign bit set to sign(A) XOR sign(B) */
        return make_float64((1ULL << 62) |
                            ((float64_val(a) ^ float64_val(b)) & (1ULL << 63)));
    }
    return float64_mul(a, b, fpst);
}

uint64_t HELPER(simd_tbl)(CPUARMState *env, uint64_t result, uint64_t indices,
                          uint32_t rn, uint32_t numregs)
{
    /* Helper function for SIMD TBL and TBX. We have to do the table
     * lookup part for the 64 bits worth of indices we're passed in.
     * result is the initial results vector (either zeroes for TBL
     * or some guest values for TBX), rn the register number where
     * the table starts, and numregs the number of registers in the table.
     * We return the results of the lookups.
     */
    int shift;

    for (shift = 0; shift < 64; shift += 8) {
        int index = extract64(indices, shift, 8);
        if (index < 16 * numregs) {
            /* Convert index (a byte offset into the virtual table
             * which is a series of 128-bit vectors concatenated)
             * into the correct vfp.regs[] element plus a bit offset
             * into that element, bearing in mind that the table
             * can wrap around from V31 to V0.
             */
            int elt = (rn * 2 + (index >> 3)) % 64;
            int bitidx = (index & 7) * 8;
            uint64_t val = extract64(env->vfp.regs[elt], bitidx, 8);

            result = deposit64(result, shift, 8, val);
        }
    }
    return result;
}

/* Helper function for 64 bit polynomial multiply case:
 * perform PolynomialMult(op1, op2) and return either the top or
 * bottom half of the 128 bit result.
 */
uint64_t HELPER(neon_pmull_64_lo)(uint64_t op1, uint64_t op2)
{
    int bitnum;
    uint64_t res = 0;

    for (bitnum = 0; bitnum < 64; bitnum++) {
        if (op1 & (1ULL << bitnum)) {
            res ^= op2 << bitnum;
        }
    }
    return res;
}
uint64_t HELPER(neon_pmull_64_hi)(uint64_t op1, uint64_t op2)
{
    int bitnum;
    uint64_t res = 0;

    /* bit 0 of op1 can't influence the high 64 bits at all */
    for (bitnum = 1; bitnum < 64; bitnum++) {
        if (op1 & (1ULL << bitnum)) {
            res ^= op2 >> (64 - bitnum);
        }
    }
    return res;
}

/* 64bit/double versions of the neon float compare functions */
uint64_t HELPER(neon_ceq_f64)(float64 a, float64 b, void *fpstp)
{
    float_status *fpst = fpstp;
    return -float64_eq_quiet(a, b, fpst);
}

uint64_t HELPER(neon_cge_f64)(float64 a, float64 b, void *fpstp)
{
    float_status *fpst = fpstp;
    return -float64_le(b, a, fpst);
}

uint64_t HELPER(neon_cgt_f64)(float64 a, float64 b, void *fpstp)
{
    float_status *fpst = fpstp;
    return -float64_lt(b, a, fpst);
}

/* Reciprocal step and sqrt step. Note that unlike the A32/T32
 * versions, these do a fully fused multiply-add or
 * multiply-add-and-halve.
 */
#define float32_two make_float32(0x40000000)
#define float32_three make_float32(0x40400000)
#define float32_one_point_five make_float32(0x3fc00000)

#define float64_two make_float64(0x4000000000000000ULL)
#define float64_three make_float64(0x4008000000000000ULL)
#define float64_one_point_five make_float64(0x3FF8000000000000ULL)

float32 HELPER(recpsf_f32)(float32 a, float32 b, void *fpstp)
{
    float_status *fpst = fpstp;

    a = float32_chs(a);
    if ((float32_is_infinity(a) && float32_is_zero(b)) ||
        (float32_is_infinity(b) && float32_is_zero(a))) {
        return float32_two;
    }
    return float32_muladd(a, b, float32_two, 0, fpst);
}

float64 HELPER(recpsf_f64)(float64 a, float64 b, void *fpstp)
{
    float_status *fpst = fpstp;

    a = float64_chs(a);
    if ((float64_is_infinity(a) && float64_is_zero(b)) ||
        (float64_is_infinity(b) && float64_is_zero(a))) {
        return float64_two;
    }
    return float64_muladd(a, b, float64_two, 0, fpst);
}

float32 HELPER(rsqrtsf_f32)(float32 a, float32 b, void *fpstp)
{
    float_status *fpst = fpstp;

    a = float32_chs(a);
    if ((float32_is_infinity(a) && float32_is_zero(b)) ||
        (float32_is_infinity(b) && float32_is_zero(a))) {
        return float32_one_point_five;
    }
    return float32_muladd(a, b, float32_three, float_muladd_halve_result, fpst);
}

float64 HELPER(rsqrtsf_f64)(float64 a, float64 b, void *fpstp)
{
    float_status *fpst = fpstp;

    a = float64_chs(a);
    if ((float64_is_infinity(a) && float64_is_zero(b)) ||
        (float64_is_infinity(b) && float64_is_zero(a))) {
        return float64_one_point_five;
    }
    return float64_muladd(a, b, float64_three, float_muladd_halve_result, fpst);
}

/* Pairwise long add: add pairs of adjacent elements into
 * double-width elements in the result (eg _s8 is an 8x8->16 op)
 */
uint64_t HELPER(neon_addlp_s8)(uint64_t a)
{
    uint64_t nsignmask = 0x0080008000800080ULL;
    uint64_t wsignmask = 0x8000800080008000ULL;
    uint64_t elementmask = 0x00ff00ff00ff00ffULL;
    uint64_t tmp1, tmp2;
    uint64_t res, signres;

    /* Extract odd elements, sign extend each to a 16 bit field */
    tmp1 = a & elementmask;
    tmp1 ^= nsignmask;
    tmp1 |= wsignmask;
    tmp1 = (tmp1 - nsignmask) ^ wsignmask;
    /* Ditto for the even elements */
    tmp2 = (a >> 8) & elementmask;
    tmp2 ^= nsignmask;
    tmp2 |= wsignmask;
    tmp2 = (tmp2 - nsignmask) ^ wsignmask;

    /* calculate the result by summing bits 0..14, 16..22, etc,
     * and then adjusting the sign bits 15, 23, etc manually.
     * This ensures the addition can't overflow the 16 bit field.
     */
    signres = (tmp1 ^ tmp2) & wsignmask;
    res = (tmp1 & ~wsignmask) + (tmp2 & ~wsignmask);
    res ^= signres;

    return res;
}

uint64_t HELPER(neon_addlp_u8)(uint64_t a)
{
    uint64_t tmp;

    tmp = a & 0x00ff00ff00ff00ffULL;
    tmp += (a >> 8) & 0x00ff00ff00ff00ffULL;
    return tmp;
}

uint64_t HELPER(neon_addlp_s16)(uint64_t a)
{
    int32_t reslo, reshi;

    reslo = (int32_t)(int16_t)a + (int32_t)(int16_t)(a >> 16);
    reshi = (int32_t)(int16_t)(a >> 32) + (int32_t)(int16_t)(a >> 48);

    return (uint32_t)reslo | (((uint64_t)reshi) << 32);
}

uint64_t HELPER(neon_addlp_u16)(uint64_t a)
{
    uint64_t tmp;

    tmp = a & 0x0000ffff0000ffffULL;
    tmp += (a >> 16) & 0x0000ffff0000ffffULL;
    return tmp;
}

/* Floating-point reciprocal exponent - see FPRecpX in ARM ARM */
float32 HELPER(frecpx_f32)(float32 a, void *fpstp)
{
    float_status *fpst = fpstp;
    uint32_t val32, sbit;
    int32_t exp;

    if (float32_is_any_nan(a)) {
        float32 nan = a;
        if (float32_is_signaling_nan(a)) {
            float_raise(float_flag_invalid, fpst);
            nan = float32_maybe_silence_nan(a);
        }
        if (fpst->default_nan_mode) {
            nan = float32_default_nan;
        }
        return nan;
    }

    val32 = float32_val(a);
    sbit = 0x80000000ULL & val32;
    exp = extract32(val32, 23, 8);

    if (exp == 0) {
        return make_float32(sbit | (0xfe << 23));
    } else {
        return make_float32(sbit | (~exp & 0xff) << 23);
    }
}

float64 HELPER(frecpx_f64)(float64 a, void *fpstp)
{
    float_status *fpst = fpstp;
    uint64_t val64, sbit;
    int64_t exp;

    if (float64_is_any_nan(a)) {
        float64 nan = a;
        if (float64_is_signaling_nan(a)) {
            float_raise(float_flag_invalid, fpst);
            nan = float64_maybe_silence_nan(a);
        }
        if (fpst->default_nan_mode) {
            nan = float64_default_nan;
        }
        return nan;
    }

    val64 = float64_val(a);
    sbit = 0x8000000000000000ULL & val64;
    exp = extract64(float64_val(a), 52, 11);

    if (exp == 0) {
        return make_float64(sbit | (0x7feULL << 52));
    } else {
        return make_float64(sbit | (~exp & 0x7ffULL) << 52);
    }
}

float32 HELPER(fcvtx_f64_to_f32)(float64 a, CPUARMState *env)
{
    /* Von Neumann rounding is implemented by using round-to-zero
     * and then setting the LSB of the result if Inexact was raised.
     */
    float32 r;
    float_status *fpst = &env->vfp.fp_status;
    float_status tstat = *fpst;
    int exflags;

    set_float_rounding_mode(float_round_to_zero, &tstat);
    set_float_exception_flags(0, &tstat);
    r = float64_to_float32(a, &tstat);
    r = float32_maybe_silence_nan(r);
    exflags = get_float_exception_flags(&tstat);
    if (exflags & float_flag_inexact) {
        r = make_float32(float32_val(r) | 1);
    }
    exflags |= get_float_exception_flags(fpst);
    set_float_exception_flags(exflags, fpst);
    return r;
}