/*
 *  M68K helper routines
 *
 *  Copyright (c) 2007 CodeSourcery
 *
 * 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 "cpu.h"
#include "exec/helper-proto.h"
#include "exec/exec-all.h"
#include "exec/cpu_ldst.h"

#if defined(CONFIG_USER_ONLY)

void m68k_cpu_do_interrupt(CPUState *cs)
{
    cs->exception_index = -1;
}

static inline void do_interrupt_m68k_hardirq(CPUM68KState *env)
{
}

#else

extern int semihosting_enabled;

/* Try to fill the TLB and return an exception if error. If retaddr is
   NULL, it means that the function was called in C code (i.e. not
   from generated code or from helper.c) */
void tlb_fill(CPUState *cs, target_ulong addr, MMUAccessType access_type,
              int mmu_idx, uintptr_t retaddr)
{
    int ret;

    ret = m68k_cpu_handle_mmu_fault(cs, addr, access_type, mmu_idx);
    if (unlikely(ret)) {
        if (retaddr) {
            /* now we have a real cpu fault */
            cpu_restore_state(cs, retaddr);
        }
        cpu_loop_exit(cs);
    }
}

static void do_rte(CPUM68KState *env)
{
    uint32_t sp;
    uint32_t fmt;

    sp = env->aregs[7];
    fmt = cpu_ldl_kernel(env, sp);
    env->pc = cpu_ldl_kernel(env, sp + 4);
    sp |= (fmt >> 28) & 3;
    env->aregs[7] = sp + 8;
    helper_set_sr(env, fmt);
}

static void do_interrupt_all(CPUM68KState *env, int is_hw)
{
    CPUState *cs = CPU(m68k_env_get_cpu(env));
    uint32_t sp;
    uint32_t fmt;
    uint32_t retaddr;
    uint32_t vector;

    fmt = 0;
    retaddr = env->pc;

    if (!is_hw) {
        switch (cs->exception_index) {
        case EXCP_RTE:
            /* Return from an exception.  */
            do_rte(env);
            return;
        case EXCP_HALT_INSN:
            cs->halted = 1;
            cs->exception_index = EXCP_HLT;
            cpu_loop_exit(cs);
            return;
        }
        if (cs->exception_index >= EXCP_TRAP0
            && cs->exception_index <= EXCP_TRAP15) {
            /* Move the PC after the trap instruction.  */
            retaddr += 2;
        }
    }

    vector = cs->exception_index << 2;

    fmt |= 0x40000000;
    fmt |= vector << 16;
    fmt |= env->sr;
    fmt |= cpu_m68k_get_ccr(env);

    env->sr |= SR_S;
    if (is_hw) {
        env->sr = (env->sr & ~SR_I) | (env->pending_level << SR_I_SHIFT);
        env->sr &= ~SR_M;
    }
    m68k_switch_sp(env);
    sp = env->aregs[7];
    fmt |= (sp & 3) << 28;

    /* ??? This could cause MMU faults.  */
    sp &= ~3;
    sp -= 4;
    cpu_stl_kernel(env, sp, retaddr);
    sp -= 4;
    cpu_stl_kernel(env, sp, fmt);
    env->aregs[7] = sp;
    /* Jump to vector.  */
    env->pc = cpu_ldl_kernel(env, env->vbr + vector);
}

void m68k_cpu_do_interrupt(CPUState *cs)
{
    M68kCPU *cpu = M68K_CPU(cs->uc, cs);
    CPUM68KState *env = &cpu->env;

    do_interrupt_all(env, 0);
}

static inline void do_interrupt_m68k_hardirq(CPUM68KState *env)
{
    do_interrupt_all(env, 1);
}
#endif

bool m68k_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
{
    M68kCPU *cpu = M68K_CPU(cs->uc, cs);
    CPUM68KState *env = &cpu->env;

    if (interrupt_request & CPU_INTERRUPT_HARD
        && ((env->sr & SR_I) >> SR_I_SHIFT) < env->pending_level) {
        /* Real hardware gets the interrupt vector via an IACK cycle
           at this point.  Current emulated hardware doesn't rely on
           this, so we provide/save the vector when the interrupt is
           first signalled.  */
        cs->exception_index = env->pending_vector;
        do_interrupt_m68k_hardirq(env);
        return true;
    }
    return false;
}

static void raise_exception_ra(CPUM68KState *env, int tt, uintptr_t raddr)
{
    CPUState *cs = CPU(m68k_env_get_cpu(env));

    cs->exception_index = tt;
    cpu_loop_exit_restore(cs, raddr);
}

static void raise_exception(CPUM68KState *env, int tt)
{
    raise_exception_ra(env, tt, 0);
}

void HELPER(raise_exception)(CPUM68KState *env, uint32_t tt)
{
    raise_exception(env, tt);
}

void HELPER(divuw)(CPUM68KState *env, int destr, uint32_t den)
{
    uint32_t num = env->dregs[destr];
    uint32_t quot, rem;

    if (den == 0) {
        raise_exception_ra(env, EXCP_DIV0, GETPC());
    }
    quot = num / den;
    rem = num % den;

    env->cc_c = 0; /* always cleared, even if overflow */
    if (quot > 0xffff) {
        env->cc_v = -1;
        /* real 68040 keeps N and unset Z on overflow,
         * whereas documentation says "undefined"
         */
        env->cc_z = 1;
        return;
    }
    env->dregs[destr] = deposit32(quot, 16, 16, rem);
    env->cc_z = (int16_t)quot;
    env->cc_n = (int16_t)quot;
    env->cc_v = 0;
}

void HELPER(divsw)(CPUM68KState *env, int destr, int32_t den)
{
    int32_t num = env->dregs[destr];
    uint32_t quot, rem;

    if (den == 0) {
        raise_exception_ra(env, EXCP_DIV0, GETPC());
    }
    quot = num / den;
    rem = num % den;

    env->cc_c = 0; /* always cleared, even if overflow */
    if (quot != (int16_t)quot) {
        env->cc_v = -1;
        /* nothing else is modified */
        /* real 68040 keeps N and unset Z on overflow,
         * whereas documentation says "undefined"
         */
        env->cc_z = 1;
        return;
    }
    env->dregs[destr] = deposit32(quot, 16, 16, rem);
    env->cc_z = (int16_t)quot;
    env->cc_n = (int16_t)quot;
    env->cc_v = 0;
}

void HELPER(divul)(CPUM68KState *env, int numr, int regr, uint32_t den)
{
    uint32_t num = env->dregs[numr];
    uint32_t quot, rem;

    if (den == 0) {
        raise_exception_ra(env, EXCP_DIV0, GETPC());
    }
    quot = num / den;
    rem = num % den;

    env->cc_c = 0;
    env->cc_z = quot;
    env->cc_n = quot;
    env->cc_v = 0;

    if (m68k_feature(env, M68K_FEATURE_CF_ISA_A)) {
        if (numr == regr) {
            env->dregs[numr] = quot;
        } else {
            env->dregs[regr] = rem;
        }
    } else {
        env->dregs[regr] = rem;
        env->dregs[numr] = quot;
    }
}

void HELPER(divsl)(CPUM68KState *env, int numr, int regr, int32_t den)
{
    int32_t num = env->dregs[numr];
    int32_t quot, rem;

    if (den == 0) {
        raise_exception_ra(env, EXCP_DIV0, GETPC());
    }
    quot = num / den;
    rem = num % den;

    env->cc_c = 0;
    env->cc_z = quot;
    env->cc_n = quot;
    env->cc_v = 0;

    if (m68k_feature(env, M68K_FEATURE_CF_ISA_A)) {
        if (numr == regr) {
            env->dregs[numr] = quot;
        } else {
            env->dregs[regr] = rem;
        }
    } else {
        env->dregs[regr] = rem;
        env->dregs[numr] = quot;
    }
}

void HELPER(divull)(CPUM68KState *env, int numr, int regr, uint32_t den)
{
    uint64_t num = deposit64(env->dregs[numr], 32, 32, env->dregs[regr]);
    uint64_t quot;
    uint32_t rem;

    if (den == 0) {
        raise_exception_ra(env, EXCP_DIV0, GETPC());
    }
    quot = num / den;
    rem = num % den;

    env->cc_c = 0; /* always cleared, even if overflow */
    if (quot > 0xffffffffULL) {
        env->cc_v = -1;
        /* real 68040 keeps N and unset Z on overflow,
         * whereas documentation says "undefined"
         */
        env->cc_z = 1;
        return;
    }
    env->cc_z = quot;
    env->cc_n = quot;
    env->cc_v = 0;

    /*
     * If Dq and Dr are the same, the quotient is returned.
     * therefore we set Dq last.
     */

    env->dregs[regr] = rem;
    env->dregs[numr] = quot;
}

void HELPER(divsll)(CPUM68KState *env, int numr, int regr, int32_t den)
{
    int64_t num = deposit64(env->dregs[numr], 32, 32, env->dregs[regr]);
    int64_t quot;
    int32_t rem;

    if (den == 0) {
        raise_exception_ra(env, EXCP_DIV0, GETPC());
    }
    quot = num / den;
    rem = num % den;

    env->cc_c = 0; /* always cleared, even if overflow */
    if (quot != (int32_t)quot) {
        env->cc_v = -1;
        /* real 68040 keeps N and unset Z on overflow,
         * whereas documentation says "undefined"
         */
        env->cc_z = 1;
        return;
    }
    env->cc_z = quot;
    env->cc_n = quot;
    env->cc_v = 0;

    /*
     * If Dq and Dr are the same, the quotient is returned.
     * therefore we set Dq last.
     */

    env->dregs[regr] = rem;
    env->dregs[numr] = quot;
}