qemu/target-m68k/helper.c

/*
 *  m68k op helpers
 * 
 *  Copyright (c) 2006-2007 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;
}

void helper_movec(CPUM68KState *env, int reg, uint32_t val)
{
    switch (reg) {
    case 0x02: /* CACR */
        /* Ignored.  */
        break;
    case 0x801: /* VBR */
        env->vbr = val;
        break;
    /* TODO: Implement control registers.  */
    default:
        cpu_abort(env, "Unimplemented control register write 0x%x = 0x%x\n",
                  reg, val);
    }
}

/* MMU */

/* TODO: This will need fixing once the MMU is implemented.  */
target_phys_addr_t cpu_get_phys_page_debug(CPUState *env, target_ulong addr)
{
    return addr;
}

#if defined(CONFIG_USER_ONLY) 

int cpu_m68k_handle_mmu_fault (CPUState *env, target_ulong address, int rw,
                               int is_user, int is_softmmu)
{
    env->exception_index = EXCP_ACCESS;
    env->mmu.ar = address;
    return 1;
}

#else

int cpu_m68k_handle_mmu_fault (CPUState *env, target_ulong address, int rw,
                               int is_user, int is_softmmu)
{
    int prot;

    address &= TARGET_PAGE_MASK;
    prot = PAGE_READ | PAGE_WRITE;
    return tlb_set_page(env, address, address, prot, is_user, is_softmmu);
}

/* Notify CPU of a pending interrupt.  Prioritization and vectoring should
   be handled by the interrupt controller.  Real hardware only requests
   the vector when the interrupt is acknowledged by the CPU.  For
   simplicitly we calculate it when the interrupt is signalled.  */
void m68k_set_irq_level(CPUM68KState *env, int level, uint8_t vector)
{
    env->pending_level = level;
    env->pending_vector = vector;
    if (level)
        cpu_interrupt(env, CPU_INTERRUPT_HARD);
    else
        cpu_reset_interrupt(env, CPU_INTERRUPT_HARD);
}

#endif