target-m68k/op_helper.c

   1 /*
   2  *  M68K helper routines
   3  *
   4  *  Copyright (c) 2007 CodeSourcery
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19 #include "cpu.h"
  20 #include "exec/helper-proto.h"
  21 #include "exec/cpu_ldst.h"
  22
  23 #if defined(CONFIG_USER_ONLY)
  24
  25 void m68k_cpu_do_interrupt(CPUState *cs)
  26 {
  27     cs->exception_index = -1;
  28 }
  29
  30 static inline void do_interrupt_m68k_hardirq(CPUM68KState *env)
  31 {
  32 }
  33
  34 #else
  35
  36 extern int semihosting_enabled;
  37
  38 /* Try to fill the TLB and return an exception if error. If retaddr is
  39    NULL, it means that the function was called in C code (i.e. not
  40    from generated code or from helper.c) */
  41 void tlb_fill(CPUState *cs, target_ulong addr, int is_write, int mmu_idx,
  42               uintptr_t retaddr)
  43 {
  44     int ret;
  45
  46     ret = m68k_cpu_handle_mmu_fault(cs, addr, is_write, mmu_idx);
  47     if (unlikely(ret)) {
  48         if (retaddr) {
  49             /* now we have a real cpu fault */
  50             cpu_restore_state(cs, retaddr);
  51         }
  52         cpu_loop_exit(cs);
  53     }
  54 }
  55
  56 static void do_rte(CPUM68KState *env)
  57 {
  58     uint32_t sp;
  59     uint32_t fmt;
  60
  61     sp = env->aregs[7];
  62     fmt = cpu_ldl_kernel(env, sp);
  63     env->pc = cpu_ldl_kernel(env, sp + 4);
  64     sp |= (fmt >> 28) & 3;
  65     env->sr = fmt & 0xffff;
  66     m68k_switch_sp(env);
  67     env->aregs[7] = sp + 8;
  68 }
  69
  70 static void do_interrupt_all(CPUM68KState *env, int is_hw)
  71 {
  72     CPUState *cs = CPU(m68k_env_get_cpu(env));
  73     uint32_t sp;
  74     uint32_t fmt;
  75     uint32_t retaddr;
  76     uint32_t vector;
  77
  78     fmt = 0;
  79     retaddr = env->pc;
  80
  81     if (!is_hw) {
  82         switch (cs->exception_index) {
  83         case EXCP_RTE:
  84             /* Return from an exception.  */
  85             do_rte(env);
  86             return;
  87         case EXCP_HALT_INSN:
  88             if (semihosting_enabled
  89                     && (env->sr & SR_S) != 0
  90                     && (env->pc & 3) == 0
  91                     && cpu_lduw_code(env, env->pc - 4) == 0x4e71
  92                     && cpu_ldl_code(env, env->pc) == 0x4e7bf000) {
  93                 env->pc += 4;
  94                 do_m68k_semihosting(env, env->dregs[0]);
  95                 return;
  96             }
  97             cs->halted = 1;
  98             cs->exception_index = EXCP_HLT;
  99             cpu_loop_exit(cs);
 100             return;
 101         }
 102         if (cs->exception_index >= EXCP_TRAP0
 103             && cs->exception_index <= EXCP_TRAP15) {
 104             /* Move the PC after the trap instruction.  */
 105             retaddr += 2;
 106         }
 107     }
 108
 109     vector = cs->exception_index << 2;
 110
 111     sp = env->aregs[7];
 112
 113     fmt |= 0x40000000;
 114     fmt |= (sp & 3) << 28;
 115     fmt |= vector << 16;
 116     fmt |= env->sr;
 117
 118     env->sr |= SR_S;
 119     if (is_hw) {
 120         env->sr = (env->sr & ~SR_I) | (env->pending_level << SR_I_SHIFT);
 121         env->sr &= ~SR_M;
 122     }
 123     m68k_switch_sp(env);
 124
 125     /* ??? This could cause MMU faults.  */
 126     sp &= ~3;
 127     sp -= 4;
 128     cpu_stl_kernel(env, sp, retaddr);
 129     sp -= 4;
 130     cpu_stl_kernel(env, sp, fmt);
 131     env->aregs[7] = sp;
 132     /* Jump to vector.  */
 133     env->pc = cpu_ldl_kernel(env, env->vbr + vector);
 134 }
 135
 136 void m68k_cpu_do_interrupt(CPUState *cs)
 137 {
 138     M68kCPU *cpu = M68K_CPU(cs);
 139     CPUM68KState *env = &cpu->env;
 140
 141     do_interrupt_all(env, 0);
 142 }
 143
 144 static inline void do_interrupt_m68k_hardirq(CPUM68KState *env)
 145 {
 146     do_interrupt_all(env, 1);
 147 }
 148 #endif
 149
 150 bool m68k_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
 151 {
 152     M68kCPU *cpu = M68K_CPU(cs);
 153     CPUM68KState *env = &cpu->env;
 154
 155     if (interrupt_request & CPU_INTERRUPT_HARD
 156         && ((env->sr & SR_I) >> SR_I_SHIFT) < env->pending_level) {
 157         /* Real hardware gets the interrupt vector via an IACK cycle
 158            at this point.  Current emulated hardware doesn't rely on
 159            this, so we provide/save the vector when the interrupt is
 160            first signalled.  */
 161         cs->exception_index = env->pending_vector;
 162         do_interrupt_m68k_hardirq(env);
 163         return true;
 164     }
 165     return false;
 166 }
 167
 168 static void raise_exception(CPUM68KState *env, int tt)
 169 {
 170     CPUState *cs = CPU(m68k_env_get_cpu(env));
 171
 172     cs->exception_index = tt;
 173     cpu_loop_exit(cs);
 174 }
 175
 176 void HELPER(raise_exception)(CPUM68KState *env, uint32_t tt)
 177 {
 178     raise_exception(env, tt);
 179 }
 180
 181 void HELPER(divu)(CPUM68KState *env, uint32_t word)
 182 {
 183     uint32_t num;
 184     uint32_t den;
 185     uint32_t quot;
 186     uint32_t rem;
 187     uint32_t flags;
 188
 189     num = env->div1;
 190     den = env->div2;
 191     /* ??? This needs to make sure the throwing location is accurate.  */
 192     if (den == 0) {
 193         raise_exception(env, EXCP_DIV0);
 194     }
 195     quot = num / den;
 196     rem = num % den;
 197     flags = 0;
 198     if (word && quot > 0xffff)
 199         flags |= CCF_V;
 200     if (quot == 0)
 201         flags |= CCF_Z;
 202     else if ((int32_t)quot < 0)
 203         flags |= CCF_N;
 204     env->div1 = quot;
 205     env->div2 = rem;
 206     env->cc_dest = flags;
 207 }
 208
 209 void HELPER(divs)(CPUM68KState *env, uint32_t word)
 210 {
 211     int32_t num;
 212     int32_t den;
 213     int32_t quot;
 214     int32_t rem;
 215     int32_t flags;
 216
 217     num = env->div1;
 218     den = env->div2;
 219     if (den == 0) {
 220         raise_exception(env, EXCP_DIV0);
 221     }
 222     quot = num / den;
 223     rem = num % den;
 224     flags = 0;
 225     if (word && quot != (int16_t)quot)
 226         flags |= CCF_V;
 227     if (quot == 0)
 228         flags |= CCF_Z;
 229     else if (quot < 0)
 230         flags |= CCF_N;
 231     env->div1 = quot;
 232     env->div2 = rem;
 233     env->cc_dest = flags;
 234 }