/*
 *  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 "qemu/osdep.h"
#include "qemu/units.h"
#include "cpu.h"
#include "exec/gdbstub.h"
#include "exec/helper-proto.h"
#include "qemu/host-utils.h"
#include "qemu/log.h"
#include "qemu/main-loop.h"
#include "qemu/bitops.h"
#include "internals.h"
#include "qemu/crc32c.h"
#include "exec/exec-all.h"
#include "exec/cpu_ldst.h"
#include "qemu/int128.h"
#include "qemu/atomic128.h"
#include "tcg/tcg.h"
#include "fpu/softfloat.h"
#include <zlib.h> /* For crc32 */

/* 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(rbit64)(uint64_t x)
{
    return revbit64(x);
}

void HELPER(msr_i_spsel)(CPUARMState *env, uint32_t imm)
{
    update_spsel(env, imm);
}

static void daif_check(CPUARMState *env, uint32_t op,
                       uint32_t imm, uintptr_t ra)
{
    /* DAIF update to PSTATE.  This is OK from EL0 only if UMA is set.   */
    if (arm_current_el(env) == 0 && !( arm_sctlr(env, 0) & SCTLR_UMA)) {
        raise_exception_ra(env, EXCP_UDEF,
                           syn_aa64_sysregtrap(0, extract32(op, 0, 3),
                                               extract32(op, 3, 3), 4,
                                               imm, 0x1f, 0),
                           exception_target_el(env), ra);
    }
}

void HELPER(msr_i_daifset)(CPUARMState *env, uint32_t imm)
{
    daif_check(env, 0x1e, imm, GETPC());
    env->daif |= (imm << 6) & PSTATE_DAIF;
}

void HELPER(msr_i_daifclear)(CPUARMState *env, uint32_t imm)
{
    daif_check(env, 0x1f, imm, GETPC());
    env->daif &= ~((imm << 6) & PSTATE_DAIF);
}

/* 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_cmph_a64)(uint32_t x, uint32_t y, void *fp_status)
{
    return float_rel_to_flags(float16_compare_quiet(x, y, fp_status));
}

uint64_t HELPER(vfp_cmpeh_a64)(uint32_t x, uint32_t y, void *fp_status)
{
    return float_rel_to_flags(float16_compare(x, y, fp_status));
}

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;

    a = float32_squash_input_denormal(a, fpst);
    b = float32_squash_input_denormal(b, fpst);

    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;

    a = float64_squash_input_denormal(a, fpst);
    b = float64_squash_input_denormal(b, fpst);

    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 register 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 *q = aa64_vfp_qreg(env, elt >> 1);
            uint64_t val = extract64(q[elt & 1], bitidx, 8);

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

/* 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 float16_two make_float16(0x4000)
#define float16_three make_float16(0x4200)
#define float16_one_point_five make_float16(0x3e00)

#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)

uint32_t HELPER(recpsf_f16)(uint32_t a, uint32_t b, void *fpstp)
{
    float_status *fpst = fpstp;

    a = float16_squash_input_denormal(a, fpst);
    b = float16_squash_input_denormal(b, fpst);

    a = float16_chs(a);
    if ((float16_is_infinity(a) && float16_is_zero(b)) ||
        (float16_is_infinity(b) && float16_is_zero(a))) {
        return float16_two;
    }
    return float16_muladd(a, b, float16_two, 0, fpst);
}

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

    a = float32_squash_input_denormal(a, fpst);
    b = float32_squash_input_denormal(b, fpst);

    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_squash_input_denormal(a, fpst);
    b = float64_squash_input_denormal(b, fpst);

    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);
}

uint32_t HELPER(rsqrtsf_f16)(uint32_t a, uint32_t b, void *fpstp)
{
    float_status *fpst = fpstp;

    a = float16_squash_input_denormal(a, fpst);
    b = float16_squash_input_denormal(b, fpst);

    a = float16_chs(a);
    if ((float16_is_infinity(a) && float16_is_zero(b)) ||
        (float16_is_infinity(b) && float16_is_zero(a))) {
        return float16_one_point_five;
    }
    return float16_muladd(a, b, float16_three, float_muladd_halve_result, fpst);
}

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

    a = float32_squash_input_denormal(a, fpst);
    b = float32_squash_input_denormal(b, fpst);

    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_squash_input_denormal(a, fpst);
    b = float64_squash_input_denormal(b, fpst);

    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 */
uint32_t HELPER(frecpx_f16)(uint32_t a, void *fpstp)
{
    float_status *fpst = fpstp;
    uint16_t val16, sbit;
    int16_t exp;

    if (float16_is_any_nan(a)) {
        float16 nan = a;
        if (float16_is_signaling_nan(a, fpst)) {
            float_raise(float_flag_invalid, fpst);
            nan = float16_silence_nan(a, fpst);
        }
        if (fpst->default_nan_mode) {
            nan = float16_default_nan(fpst);
        }
        return nan;
    }

    a = float16_squash_input_denormal(a, fpst);

    val16 = float16_val(a);
    sbit = 0x8000 & val16;
    exp = extract32(val16, 10, 5);

    if (exp == 0) {
        return make_float16(deposit32(sbit, 10, 5, 0x1e));
    } else {
        return make_float16(deposit32(sbit, 10, 5, ~exp));
    }
}

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, fpst)) {
            float_raise(float_flag_invalid, fpst);
            nan = float32_silence_nan(a, fpst);
        }
        if (fpst->default_nan_mode) {
            nan = float32_default_nan(fpst);
        }
        return nan;
    }

    a = float32_squash_input_denormal(a, fpst);

    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, fpst)) {
            float_raise(float_flag_invalid, fpst);
            nan = float64_silence_nan(a, fpst);
        }
        if (fpst->default_nan_mode) {
            nan = float64_default_nan(fpst);
        }
        return nan;
    }

    a = float64_squash_input_denormal(a, fpst);

    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);
    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;
}

/* 64-bit versions of the CRC helpers.  Note that although the operation
 * (and the prototypes of crc32c() and crc32() mean that only the bottom
 * 32 bits of the accumulator and result are used, we pass and return
 * uint64_t for convenience of the generated code.  Unlike the 32-bit
 * instruction set versions, val may genuinely have 64 bits of data in it. 
 * The upper bytes of val (above the number specified by 'bytes') must have
 * been zeroed out by the caller. 
 */
uint64_t HELPER(crc32_64)(uint64_t acc, uint64_t val, uint32_t bytes)
{
    uint8_t buf[8];

    stq_le_p(buf, val);

    /* zlib crc32 converts the accumulator and output to one's complement.   */
    return crc32(acc ^ 0xffffffff, buf, bytes) ^ 0xffffffff;
}

uint64_t HELPER(crc32c_64)(uint64_t acc, uint64_t val, uint32_t bytes)
{
    uint8_t buf[8];

    stq_le_p(buf, val);

    /* Linux crc32c converts the output to one's complement.   */
    return crc32c(acc, buf, bytes) ^ 0xffffffff;
}

uint64_t HELPER(paired_cmpxchg64_le)(CPUARMState *env, uint64_t addr,
                                     uint64_t new_lo, uint64_t new_hi)
{
    Int128 cmpv = int128_make128(env->exclusive_val, env->exclusive_high);
    Int128 newv = int128_make128(new_lo, new_hi);
    Int128 oldv;
    uintptr_t ra = GETPC();
    uint64_t o0, o1;
    bool success;

#ifdef CONFIG_USER_ONLY
    /* ???  Enforce alignment.   */
    uint64_t *haddr = g2h(addr);

    set_helper_retaddr(ra);
    o0 = ldq_le_p(haddr + 0);
    o1 = ldq_le_p(haddr + 1);
    oldv = int128_make128(o0, o1);

    success = int128_eq(oldv, cmpv);
    if (success) {
        stq_le_p(haddr + 0, int128_getlo(newv));
        stq_le_p(haddr + 1, int128_gethi(newv));
    }
    clear_helper_retaddr();
#else
    int mem_idx = cpu_mmu_index(env, false);
    TCGMemOpIdx oi0 = make_memop_idx(MO_LEQ | MO_ALIGN_16, mem_idx);
    TCGMemOpIdx oi1 = make_memop_idx(MO_LEQ, mem_idx);

    o0 = helper_le_ldq_mmu(env, addr + 0, oi0, ra);
    o1 = helper_le_ldq_mmu(env, addr + 8, oi1, ra);
    oldv = int128_make128(o0, o1);

    success = int128_eq(oldv, cmpv);
    if (success) {
        helper_le_stq_mmu(env, addr + 0, int128_getlo(newv), oi1, ra);
        helper_le_stq_mmu(env, addr + 8, int128_gethi(newv), oi1, ra);
    }
#endif

    return ! success;
}

uint64_t HELPER(paired_cmpxchg64_le_parallel)(CPUARMState *env, uint64_t addr,
                                              uint64_t new_lo, uint64_t new_hi)
{
    Int128 oldv, cmpv, newv;
    uintptr_t ra = GETPC();
    bool success;
    int mem_idx;
    TCGMemOpIdx oi;

    assert(HAVE_CMPXCHG128);

    mem_idx = cpu_mmu_index(env, false);
    oi = make_memop_idx(MO_LEQ | MO_ALIGN_16, mem_idx);

    cmpv = int128_make128(env->exclusive_val, env->exclusive_high);
    newv = int128_make128(new_lo, new_hi);
    oldv = helper_atomic_cmpxchgo_le_mmu(env, addr, cmpv, newv, oi, ra);

    success = int128_eq(oldv, cmpv);
    return ! success;
}

uint64_t HELPER(paired_cmpxchg64_be)(CPUARMState *env, uint64_t addr,
                                     uint64_t new_lo, uint64_t new_hi)
{
    /*
     * High and low need to be switched here because this is not actually a
     * 128bit store but two doublewords stored consecutively
     */
    Int128 cmpv = int128_make128(env->exclusive_high, env->exclusive_val);
    Int128 newv = int128_make128(new_hi, new_lo);
    Int128 oldv;
    uintptr_t ra = GETPC();
    uint64_t o0, o1;
    bool success;

#ifdef CONFIG_USER_ONLY
    /* ???  Enforce alignment.   */
    uint64_t *haddr = g2h(addr);

    set_helper_retaddr(ra);
    o1 = ldq_be_p(haddr + 0);
    o0 = ldq_be_p(haddr + 1);
    oldv = int128_make128(o0, o1);

    success = int128_eq(oldv, cmpv);
    if (success) {
        stq_be_p(haddr + 0, int128_gethi(newv));
        stq_be_p(haddr + 1, int128_getlo(newv));
    }
    clear_helper_retaddr();
#else
    int mem_idx = cpu_mmu_index(env, false);
    TCGMemOpIdx oi0 = make_memop_idx(MO_BEQ | MO_ALIGN_16, mem_idx);
    TCGMemOpIdx oi1 = make_memop_idx(MO_BEQ, mem_idx);

    o1 = helper_be_ldq_mmu(env, addr + 0, oi0, ra);
    o0 = helper_be_ldq_mmu(env, addr + 8, oi1, ra);
    oldv = int128_make128(o0, o1);

    success = int128_eq(oldv, cmpv);
    if (success) {
        helper_be_stq_mmu(env, addr + 0, int128_gethi(newv), oi1, ra);
        helper_be_stq_mmu(env, addr + 8, int128_getlo(newv), oi1, ra);
    }
#endif

    return ! success;
}

uint64_t HELPER(paired_cmpxchg64_be_parallel)(CPUARMState *env, uint64_t addr,
                                              uint64_t new_lo, uint64_t new_hi)
{
    Int128 oldv, cmpv, newv;
    uintptr_t ra = GETPC();
    bool success;
    int mem_idx;
    TCGMemOpIdx oi;

    assert(HAVE_CMPXCHG128);

    mem_idx = cpu_mmu_index(env, false);
    oi = make_memop_idx(MO_BEQ | MO_ALIGN_16, mem_idx);

    /*
     * High and low need to be switched here because this is not actually a
     * 128bit store but two doublewords stored consecutively
     */
    cmpv = int128_make128(env->exclusive_high, env->exclusive_val);
    newv = int128_make128(new_hi, new_lo);
    oldv = helper_atomic_cmpxchgo_be_mmu(env, addr, cmpv, newv, oi, ra);

    success = int128_eq(oldv, cmpv);
    return ! success;
}

/* Writes back the old data into Rs.   */
void HELPER(casp_le_parallel)(CPUARMState *env, uint32_t rs, uint64_t addr,
                              uint64_t new_lo, uint64_t new_hi)
{
    Int128 oldv, cmpv, newv;
    uintptr_t ra = GETPC();
    int mem_idx;
    TCGMemOpIdx oi;

    assert(HAVE_CMPXCHG128);

    mem_idx = cpu_mmu_index(env, false);
    oi = make_memop_idx(MO_LEQ | MO_ALIGN_16, mem_idx);

    cmpv = int128_make128(env->xregs[rs], env->xregs[rs + 1]);
    newv = int128_make128(new_lo, new_hi);
    oldv = helper_atomic_cmpxchgo_le_mmu(env, addr, cmpv, newv, oi, ra);

    env->xregs[rs] = int128_getlo(oldv);
    env->xregs[rs + 1] = int128_gethi(oldv);
}

void HELPER(casp_be_parallel)(CPUARMState *env, uint32_t rs, uint64_t addr,
                              uint64_t new_hi, uint64_t new_lo)
{
    Int128 oldv, cmpv, newv;
    uintptr_t ra = GETPC();
    int mem_idx;
    TCGMemOpIdx oi;

    assert(HAVE_CMPXCHG128);

    mem_idx = cpu_mmu_index(env, false);
    oi = make_memop_idx(MO_LEQ | MO_ALIGN_16, mem_idx);

    cmpv = int128_make128(env->xregs[rs + 1], env->xregs[rs]);
    newv = int128_make128(new_lo, new_hi);
    oldv = helper_atomic_cmpxchgo_be_mmu(env, addr, cmpv, newv, oi, ra);

    env->xregs[rs + 1] = int128_getlo(oldv);
    env->xregs[rs] = int128_gethi(oldv);
}

/*
 * AdvSIMD half-precision
 */

#define ADVSIMD_HELPER(name, suffix) HELPER(glue(glue(advsimd_, name), suffix))

#define ADVSIMD_HALFOP(name) \
uint32_t ADVSIMD_HELPER(name, h)(uint32_t a, uint32_t b, void *fpstp) \
{ \
    float_status *fpst = fpstp; \
    return float16_ ## name(a, b, fpst);    \
}

ADVSIMD_HALFOP(add)
ADVSIMD_HALFOP(sub)
ADVSIMD_HALFOP(mul)
ADVSIMD_HALFOP(div)
ADVSIMD_HALFOP(min)
ADVSIMD_HALFOP(max)
ADVSIMD_HALFOP(minnum)
ADVSIMD_HALFOP(maxnum)

#define ADVSIMD_TWOHALFOP(name)                                         \
uint32_t ADVSIMD_HELPER(name, 2h)(uint32_t two_a, uint32_t two_b, void *fpstp) \
{ \
    float16  a1, a2, b1, b2;                        \
    uint32_t r1, r2;                                \
    float_status *fpst = fpstp;                     \
    a1 = extract32(two_a, 0, 16);                   \
    a2 = extract32(two_a, 16, 16);                  \
    b1 = extract32(two_b, 0, 16);                   \
    b2 = extract32(two_b, 16, 16);                  \
    r1 = float16_ ## name(a1, b1, fpst);            \
    r2 = float16_ ## name(a2, b2, fpst);            \
    return deposit32(r1, 16, 16, r2);               \
}

ADVSIMD_TWOHALFOP(add)
ADVSIMD_TWOHALFOP(sub)
ADVSIMD_TWOHALFOP(mul)
ADVSIMD_TWOHALFOP(div)
ADVSIMD_TWOHALFOP(min)
ADVSIMD_TWOHALFOP(max)
ADVSIMD_TWOHALFOP(minnum)
ADVSIMD_TWOHALFOP(maxnum)

/* Data processing - scalar floating-point and advanced SIMD */
static float16 float16_mulx(float16 a, float16 b, void *fpstp)
{
    float_status *fpst = fpstp;

    a = float16_squash_input_denormal(a, fpst);
    b = float16_squash_input_denormal(b, fpst);

    if ((float16_is_zero(a) && float16_is_infinity(b)) ||
        (float16_is_infinity(a) && float16_is_zero(b))) {
        /* 2.0 with the sign bit set to sign(A) XOR sign(B) */
        return make_float16((1U << 14) |
                            ((float16_val(a) ^ float16_val(b)) & (1U << 15)));
    }
    return float16_mul(a, b, fpst);
}

ADVSIMD_HALFOP(mulx)
ADVSIMD_TWOHALFOP(mulx)

/* fused multiply-accumulate */
uint32_t HELPER(advsimd_muladdh)(uint32_t a, uint32_t b, uint32_t c,
                                 void *fpstp)
{
    float_status *fpst = fpstp;
    return float16_muladd(a, b, c, 0, fpst);
}

uint32_t HELPER(advsimd_muladd2h)(uint32_t two_a, uint32_t two_b,
                                  uint32_t two_c, void *fpstp)
{
    float_status *fpst = fpstp;
    float16  a1, a2, b1, b2, c1, c2;
    uint32_t r1, r2;
    a1 = extract32(two_a, 0, 16);
    a2 = extract32(two_a, 16, 16);
    b1 = extract32(two_b, 0, 16);
    b2 = extract32(two_b, 16, 16);
    c1 = extract32(two_c, 0, 16);
    c2 = extract32(two_c, 16, 16);
    r1 = float16_muladd(a1, b1, c1, 0, fpst);
    r2 = float16_muladd(a2, b2, c2, 0, fpst);
    return deposit32(r1, 16, 16, r2);
}

/*
 * Floating point comparisons produce an integer result.  Softfloat
 * routines return float_relation types which we convert to the 0/-1
 * Neon requires. 
 */

#define ADVSIMD_CMPRES(test) (test) ?  0xffff : 0

uint32_t HELPER(advsimd_ceq_f16)(uint32_t a, uint32_t b, void *fpstp)
{
    float_status *fpst = fpstp;
    int compare = float16_compare_quiet(a, b, fpst);
    return ADVSIMD_CMPRES(compare == float_relation_equal);
}

uint32_t HELPER(advsimd_cge_f16)(uint32_t a, uint32_t b, void *fpstp)
{
    float_status *fpst = fpstp;
    int compare = float16_compare(a, b, fpst);
    return ADVSIMD_CMPRES(compare == float_relation_greater ||
                          compare == float_relation_equal);
}

uint32_t HELPER(advsimd_cgt_f16)(uint32_t a, uint32_t b, void *fpstp)
{
    float_status *fpst = fpstp;
    int compare = float16_compare(a, b, fpst);
    return ADVSIMD_CMPRES(compare == float_relation_greater);
}

uint32_t HELPER(advsimd_acge_f16)(uint32_t a, uint32_t b, void *fpstp)
{
    float_status *fpst = fpstp;
    float16 f0 = float16_abs(a);
    float16 f1 = float16_abs(b);
    int compare = float16_compare(f0, f1, fpst);
    return ADVSIMD_CMPRES(compare == float_relation_greater ||
                          compare == float_relation_equal);
}

uint32_t HELPER(advsimd_acgt_f16)(uint32_t a, uint32_t b, void *fpstp)
{
    float_status *fpst = fpstp;
    float16 f0 = float16_abs(a);
    float16 f1 = float16_abs(b);
    int compare = float16_compare(f0, f1, fpst);
    return ADVSIMD_CMPRES(compare == float_relation_greater);
}

/* round to integral */
uint32_t HELPER(advsimd_rinth_exact)(uint32_t x, void *fp_status)
{
    return float16_round_to_int(x, fp_status);
}

uint32_t HELPER(advsimd_rinth)(uint32_t x, void *fp_status)
{
    int old_flags = get_float_exception_flags(fp_status), new_flags;
    float16 ret;

    ret = float16_round_to_int(x, fp_status);

    /* Suppress any inexact exceptions the conversion produced */
    if (!( old_flags & float_flag_inexact)) {
        new_flags = get_float_exception_flags(fp_status);
        set_float_exception_flags(new_flags & ~float_flag_inexact, fp_status);
    }

    return ret;
}

/*
 * Half-precision floating point conversion functions
 *
 * There are a multitude of conversion functions with various
 * different rounding modes.  This is dealt with by the calling code
 * setting the mode appropriately before calling the helper. 
 */

uint32_t HELPER(advsimd_f16tosinth)(uint32_t a, void *fpstp)
{
    float_status *fpst = fpstp;

    /* Invalid if we are passed a NaN */
    if (float16_is_any_nan(a)) {
        float_raise(float_flag_invalid, fpst);
        return 0;
    }
    return float16_to_int16(a, fpst);
}

uint32_t HELPER(advsimd_f16touinth)(uint32_t a, void *fpstp)
{
    float_status *fpst = fpstp;

    /* Invalid if we are passed a NaN */
    if (float16_is_any_nan(a)) {
        float_raise(float_flag_invalid, fpst);
        return 0;
    }
    return float16_to_uint16(a, fpst);
}

static int el_from_spsr(uint32_t spsr)
{
    /* Return the exception level that this SPSR is requesting a return to,
     * or -1 if it is invalid (an illegal return)
     */
    if (spsr & PSTATE_nRW) {
        switch (spsr & CPSR_M) {
        case ARM_CPU_MODE_USR:
            return 0;
        case ARM_CPU_MODE_HYP:
            return 2;
        case ARM_CPU_MODE_FIQ:
        case ARM_CPU_MODE_IRQ:
        case ARM_CPU_MODE_SVC:
        case ARM_CPU_MODE_ABT:
        case ARM_CPU_MODE_UND:
        case ARM_CPU_MODE_SYS:
            return 1;
        case ARM_CPU_MODE_MON:
            /* Returning to Mon from AArch64 is never possible,
             * so this is an illegal return. 
             */
        default:
            return -1;
        }
    } else {
        if (extract32(spsr, 1, 1)) {
            /* Return with reserved M[1] bit set */
            return -1;
        }
        if (extract32(spsr, 0, 4) == 1) {
            /* return to EL0 with M[0] bit set */
            return -1;
        }
        return extract32(spsr, 2, 2);
    }
}

void HELPER(exception_return)(CPUARMState *env, uint64_t new_pc)
{
    int cur_el = arm_current_el(env);
    unsigned int spsr_idx = aarch64_banked_spsr_index(cur_el);
    uint32_t mask, spsr = env->banked_spsr[spsr_idx];
    int new_el;
    bool return_to_aa64 = (spsr & PSTATE_nRW) == 0;

    aarch64_save_sp(env, cur_el);

    arm_clear_exclusive(env);

    /* We must squash the PSTATE.SS bit to zero unless both of the
     * following hold:
     *  1.  debug exceptions are currently disabled
     *  2.  singlestep will be active in the EL we return to
     * We check 1 here and 2 after we've done the pstate/cpsr write() to
     * transition to the EL we're going to. 
     */
    if (arm_generate_debug_exceptions(env)) {
        spsr &= ~PSTATE_SS;
    }

    new_el = el_from_spsr(spsr);
    if (new_el == -1) {
        goto illegal_return;
    }
    if (new_el > cur_el
        || (new_el == 2 && ! arm_feature(env, ARM_FEATURE_EL2))) {
        /* Disallow return to an EL which is unimplemented or higher
         * than the current one. 
         */
        goto illegal_return;
    }

    if (new_el ! = 0 && arm_el_is_aa64(env, new_el) ! = return_to_aa64) {
        /* Return to an EL which is configured for a different register width */
        goto illegal_return;
    }

    if (new_el == 2 && arm_is_secure_below_el3(env)) {
        /* Return to the non-existent secure-EL2 */
        goto illegal_return;
    }

    if (new_el == 1 && (arm_hcr_el2_eff(env) & HCR_TGE)) {
        goto illegal_return;
    }

    qemu_mutex_lock_iothread();
    arm_call_pre_el_change_hook(env_archcpu(env));
    qemu_mutex_unlock_iothread();

    if (! return_to_aa64) {
        env->aarch64 = 0;
        /* We do a raw CPSR write because aarch64_sync_64_to_32()
         * will sort the register banks out for us, and we've already
         * caught all the bad-mode cases in el_from_spsr(). 
         */
        mask = aarch32_cpsr_valid_mask(env->features, &env_archcpu(env)->isar);
        cpsr_write(env, spsr, mask, CPSRWriteRaw);
        if (! arm_singlestep_active(env)) {
            env->uncached_cpsr &= ~PSTATE_SS;
        }
        aarch64_sync_64_to_32(env);

        if (spsr & CPSR_T) {
            env->regs[15] = new_pc & ~0x1;
        } else {
            env->regs[15] = new_pc & ~0x3;
        }
        helper_rebuild_hflags_a32(env, new_el);
        qemu_log_mask(CPU_LOG_INT, "Exception return from AArch64 EL%d to "
                      "AArch32 EL%d PC 0x%" PRIx32 "\n",
                      cur_el, new_el, env->regs[15]);
    } else {
        int tbii;

        env->aarch64 = 1;
        spsr &= aarch64_pstate_valid_mask(&env_archcpu(env)->isar);
        pstate_write(env, spsr);
        if (! arm_singlestep_active(env)) {
            env->pstate &= ~PSTATE_SS;
        }
        aarch64_restore_sp(env, new_el);
        helper_rebuild_hflags_a64(env, new_el);

        /*
         * Apply TBI to the exception return address.   We had to delay this
         * until after we selected the new EL, so that we could select the
         * correct TBI+TBID bits.   This is made easier by waiting until after
         * the hflags rebuild, since we can pull the composite TBII field
         * from there. 
         */
        tbii = FIELD_EX32(env->hflags, TBFLAG_A64, TBII);
        if ((tbii >> extract64(new_pc, 55, 1)) & 1) {
            /* TBI is enabled. */ 
            int core_mmu_idx = cpu_mmu_index(env, false);
            if (regime_has_2_ranges(core_to_aa64_mmu_idx(core_mmu_idx))) {
                new_pc = sextract64(new_pc, 0, 56);
            } else {
                new_pc = extract64(new_pc, 0, 56);
            }
        }
        env->pc = new_pc;

        qemu_log_mask(CPU_LOG_INT, "Exception return from AArch64 EL%d to "
                      "AArch64 EL%d PC 0x%" PRIx64 "\n",
                      cur_el, new_el, env->pc);
    }

    /*
     * Note that cur_el can never be 0.   If new_el is 0, then
     * el0_a64 is return_to_aa64, else el0_a64 is ignored. 
     */
    aarch64_sve_change_el(env, cur_el, new_el, return_to_aa64);

    qemu_mutex_lock_iothread();
    arm_call_el_change_hook(env_archcpu(env));
    qemu_mutex_unlock_iothread();

    return;

illegal_return:
    /* Illegal return events of various kinds have architecturally
     * mandated behaviour:
     * restore NZCV and DAIF from SPSR_ELx
     * set PSTATE.IL
     * restore PC from ELR_ELx
     * no change to exception level, execution state or stack pointer
     */
    env->pstate |= PSTATE_IL;
    env->pc = new_pc;
    spsr &= PSTATE_NZCV | PSTATE_DAIF;
    spsr |= pstate_read(env) & ~(PSTATE_NZCV | PSTATE_DAIF);
    pstate_write(env, spsr);
    if (! arm_singlestep_active(env)) {
        env->pstate &= ~PSTATE_SS;
    }
    qemu_log_mask(LOG_GUEST_ERROR, "Illegal exception return at EL%d: "
                  "resuming execution at 0x%" PRIx64 "\n", cur_el, env->pc);
}

/*
 * Square Root and Reciprocal square root
 */

uint32_t HELPER(sqrt_f16)(uint32_t a, void *fpstp)
{
    float_status *s = fpstp;

    return float16_sqrt(a, s);
}

void HELPER(dc_zva)(CPUARMState *env, uint64_t vaddr_in)
{
    /*
     * Implement DC ZVA, which zeroes a fixed-length block of memory. 
     * Note that we do not implement the (architecturally mandated)
     * alignment fault for attempts to use this on Device memory
     * (which matches the usual QEMU behaviour of not implementing either
     * alignment faults or any memory attribute handling). 
     */

    ARMCPU *cpu = env_archcpu(env);
    uint64_t blocklen = 4 << cpu->dcz_blocksize;
    uint64_t vaddr = vaddr_in & ~(blocklen - 1);

#ifndef CONFIG_USER_ONLY
    {
        /*
         * Slightly awkwardly, QEMU's TARGET_PAGE_SIZE may be less than
         * the block size so we might have to do more than one TLB lookup. 
         * We know that in fact for any v8 CPU the page size is at least 4K
         * and the block size must be 2K or less, but TARGET_PAGE_SIZE is only
         * 1K as an artefact of legacy v5 subpage support being present in the
         * same QEMU executable.  So in practice the hostaddr[] array has
         * two entries, given the current setting of TARGET_PAGE_BITS_MIN. 
         */
        int maxidx = DIV_ROUND_UP(blocklen, TARGET_PAGE_SIZE);
        void *hostaddr[DIV_ROUND_UP(2 * KiB, 1 << TARGET_PAGE_BITS_MIN)];
        int try, i;
        unsigned mmu_idx = cpu_mmu_index(env, false);
        TCGMemOpIdx oi = make_memop_idx(MO_UB, mmu_idx);

        assert(maxidx <= ARRAY_SIZE(hostaddr));

        for (try = 0; try < 2; try++) {

            for (i = 0; i < maxidx; i++) {
                hostaddr[i] = tlb_vaddr_to_host(env,
                                                vaddr + TARGET_PAGE_SIZE * i,
                                                1, mmu_idx);
                if (! hostaddr[i]) {
                    break;
                }
            }
            if (i == maxidx) {
                /*
                 * If it's all in the TLB it's fair game for just writing to;
                 * we know we don't need to update dirty status, etc. 
                 */
                for (i = 0; i < maxidx - 1; i++) {
                    memset(hostaddr[i], 0, TARGET_PAGE_SIZE);
                }
                memset(hostaddr[i], 0, blocklen - (i * TARGET_PAGE_SIZE));
                return;
            }
            /*
             * OK, try a store and see if we can populate the tlb.  This
             * might cause an exception if the memory isn't writable,
             * in which case we will longjmp out of here.  We must for
             * this purpose use the actual register value passed to us
             * so that we get the fault address right. 
             */
            helper_ret_stb_mmu(env, vaddr_in, 0, oi, GETPC());
            /* Now we can populate the other TLB entries, if any */
            for (i = 0; i < maxidx; i++) {
                uint64_t va = vaddr + TARGET_PAGE_SIZE * i;
                if (va ! = (vaddr_in & TARGET_PAGE_MASK)) {
                    helper_ret_stb_mmu(env, va, 0, oi, GETPC());
                }
            }
        }

        /*
         * Slow path (probably attempt to do this to an I/O device or
         * similar, or clearing of a block of code we have translations
         * cached for).  Just do a series of byte writes as the architecture
         * demands.  It's not worth trying to use a cpu_physical_memory_map(),
         * memset(), unmap() sequence here because:
         *  + we'd need to account for the blocksize being larger than a page
         *  + the direct-RAM access case is almost always going to be dealt
         *    with in the fastpath code above, so there's no speed benefit
         *  + we would have to deal with the map returning NULL because the
         *    bounce buffer was in use
         */
        for (i = 0; i < blocklen; i++) {
            helper_ret_stb_mmu(env, vaddr + i, 0, oi, GETPC());
        }
    }
#else
    memset(g2h(vaddr), 0, blocklen);
#endif
}
