Archipelago » qemu

/*

 *  m68k op helpers

 * 

 *  Copyright (c) 2006 CodeSourcery

 *  Written by Paul Brook

 *

 * 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

 * 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, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include <stdio.h>

#include "config.h"

#include "cpu.h"

#include "exec-all.h"

void cpu_m68k_flush_flags(CPUM68KState *env, int cc_op)

{

    int flags;

    uint32_t src;

    uint32_t dest;

    uint32_t tmp;

#define HIGHBIT 0x80000000u

#define SET_NZ(x) do { \

    if ((x) == 0) \

        flags |= CCF_Z; \

    else if ((int32_t)(x) < 0) \

        flags |= CCF_N; \

    } while (0)

#define SET_FLAGS_SUB(type, utype) do { \

    SET_NZ((type)dest); \

    tmp = dest + src; \

    if ((utype) tmp < (utype) src) \

        flags |= CCF_C; \

    if ((1u << (sizeof(type) * 8 - 1)) & (tmp ^ dest) & (tmp ^ src)) \

        flags |= CCF_V; \

    } while (0)

    flags = 0;

    src = env->cc_src;

    dest = env->cc_dest;

    switch (cc_op) {

    case CC_OP_FLAGS:

        flags = dest;

        break;

    case CC_OP_LOGIC:

        SET_NZ(dest);

        break;

    case CC_OP_ADD:

        SET_NZ(dest);

        if (dest < src)

            flags |= CCF_C;

        tmp = dest - src;

        if (HIGHBIT & (src ^ dest) & ~(tmp ^ src))

            flags |= CCF_V;

        break;

    case CC_OP_SUB:

        SET_FLAGS_SUB(int32_t, uint32_t);

        break;

    case CC_OP_CMPB:

        SET_FLAGS_SUB(int8_t, uint8_t);

        break;

    case CC_OP_CMPW:

        SET_FLAGS_SUB(int16_t, uint16_t);

        break;

    case CC_OP_ADDX:

        SET_NZ(dest);

        if (dest <= src)

            flags |= CCF_C;

        tmp = dest - src - 1;

        if (HIGHBIT & (src ^ dest) & ~(tmp ^ src))

            flags |= CCF_V;

        break;

    case CC_OP_SUBX:

        SET_NZ(dest);

        tmp = dest + src + 1;

        if (tmp <= src)

            flags |= CCF_C;

        if (HIGHBIT & (tmp ^ dest) & (tmp ^ src))

            flags |= CCF_V;

        break;

    case CC_OP_SHL:

        if (src >= 32) {

            SET_NZ(0);

        } else {

            tmp = dest << src;

            SET_NZ(tmp);

        }

        if (src && src <= 32 && (dest & (1 << (32 - src))))

            flags |= CCF_C;

        break;

    case CC_OP_SHR:

        if (src >= 32) {

            SET_NZ(0);

        } else {

            tmp = dest >> src;

            SET_NZ(tmp);

        }

        if (src && src <= 32 && ((dest >> (src - 1)) & 1))

            flags |= CCF_C;

        break;

    case CC_OP_SAR:

        if (src >= 32) {

            SET_NZ(-1);

        } else {

            tmp = (int32_t)dest >> src;

            SET_NZ(tmp);

        }

        if (src && src <= 32 && (((int32_t)dest >> (src - 1)) & 1))

            flags |= CCF_C;

        break;

    default:

        cpu_abort(env, "Bad CC_OP %d", cc_op);

    }

    env->cc_op = CC_OP_FLAGS;

    env->cc_dest = flags;

}

float64 helper_sub_cmpf64(CPUM68KState *env, float64 src0, float64 src1)

{

    /* ??? This may incorrectly raise exceptions.  */

    /* ??? Should flush denormals to zero.  */

    float64 res;

    res = float64_sub(src0, src1, &env->fp_status);

    if (float64_is_nan(res)) {

        /* +/-inf compares equal against itself, but sub returns nan.  */

        if (!float64_is_nan(src0)

            && !float64_is_nan(src1)) {

            res = 0;

            if (float64_lt_quiet(src0, res, &env->fp_status))

                res = float64_chs(res);

        }

    }

    return res;

}