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 "qemu/osdep.h"
  20 #include "cpu.h"
  21 #include "exec/helper-proto.h"
  22 #include "exec/exec-all.h"
  23 #include "exec/cpu_ldst.h"
  24 #include "exec/semihost.h"
  25
  26 #if defined(CONFIG_USER_ONLY)
  27
  28 void m68k_cpu_do_interrupt(CPUState *cs)
  29 {
  30     cs->exception_index = -1;
  31 }
  32
  33 static inline void do_interrupt_m68k_hardirq(CPUM68KState *env)
  34 {
  35 }
  36
  37 #else
  38
  39 /* Try to fill the TLB and return an exception if error. If retaddr is
  40    NULL, it means that the function was called in C code (i.e. not
  41    from generated code or from helper.c) */
  42 void tlb_fill(CPUState *cs, target_ulong addr, MMUAccessType access_type,
  43               int mmu_idx, uintptr_t retaddr)
  44 {
  45     int ret;
  46
  47     ret = m68k_cpu_handle_mmu_fault(cs, addr, access_type, mmu_idx);
  48     if (unlikely(ret)) {
  49         if (retaddr) {
  50             /* now we have a real cpu fault */
  51             cpu_restore_state(cs, retaddr);
  52         }
  53         cpu_loop_exit(cs);
  54     }
  55 }
  56
  57 static void do_rte(CPUM68KState *env)
  58 {
  59     uint32_t sp;
  60     uint32_t fmt;
  61
  62     sp = env->aregs[7];
  63     fmt = cpu_ldl_kernel(env, sp);
  64     env->pc = cpu_ldl_kernel(env, sp + 4);
  65     sp |= (fmt >> 28) & 3;
  66     env->aregs[7] = sp + 8;
  67
  68     helper_set_sr(env, fmt);
  69 }
  70
  71 static void do_interrupt_all(CPUM68KState *env, int is_hw)
  72 {
  73     CPUState *cs = CPU(m68k_env_get_cpu(env));
  74     uint32_t sp;
  75     uint32_t fmt;
  76     uint32_t retaddr;
  77     uint32_t vector;
  78
  79     fmt = 0;
  80     retaddr = env->pc;
  81
  82     if (!is_hw) {
  83         switch (cs->exception_index) {
  84         case EXCP_RTE:
  85             /* Return from an exception.  */
  86             do_rte(env);
  87             return;
  88         case EXCP_HALT_INSN:
  89             if (semihosting_enabled()
  90                     && (env->sr & SR_S) != 0
  91                     && (env->pc & 3) == 0
  92                     && cpu_lduw_code(env, env->pc - 4) == 0x4e71
  93                     && cpu_ldl_code(env, env->pc) == 0x4e7bf000) {
  94                 env->pc += 4;
  95                 do_m68k_semihosting(env, env->dregs[0]);
  96                 return;
  97             }
  98             cs->halted = 1;
  99             cs->exception_index = EXCP_HLT;
 100             cpu_loop_exit(cs);
 101             return;
 102         }
 103         if (cs->exception_index >= EXCP_TRAP0
 104             && cs->exception_index <= EXCP_TRAP15) {
 105             /* Move the PC after the trap instruction.  */
 106             retaddr += 2;
 107         }
 108     }
 109
 110     vector = cs->exception_index << 2;
 111
 112     fmt |= 0x40000000;
 113     fmt |= vector << 16;
 114     fmt |= env->sr;
 115     fmt |= cpu_m68k_get_ccr(env);
 116
 117     env->sr |= SR_S;
 118     if (is_hw) {
 119         env->sr = (env->sr & ~SR_I) | (env->pending_level << SR_I_SHIFT);
 120         env->sr &= ~SR_M;
 121     }
 122     m68k_switch_sp(env);
 123     sp = env->aregs[7];
 124     fmt |= (sp & 3) << 28;
 125
 126     /* ??? This could cause MMU faults.  */
 127     sp &= ~3;
 128     sp -= 4;
 129     cpu_stl_kernel(env, sp, retaddr);
 130     sp -= 4;
 131     cpu_stl_kernel(env, sp, fmt);
 132     env->aregs[7] = sp;
 133     /* Jump to vector.  */
 134     env->pc = cpu_ldl_kernel(env, env->vbr + vector);
 135 }
 136
 137 void m68k_cpu_do_interrupt(CPUState *cs)
 138 {
 139     M68kCPU *cpu = M68K_CPU(cs);
 140     CPUM68KState *env = &cpu->env;
 141
 142     do_interrupt_all(env, 0);
 143 }
 144
 145 static inline void do_interrupt_m68k_hardirq(CPUM68KState *env)
 146 {
 147     do_interrupt_all(env, 1);
 148 }
 149 #endif
 150
 151 bool m68k_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
 152 {
 153     M68kCPU *cpu = M68K_CPU(cs);
 154     CPUM68KState *env = &cpu->env;
 155
 156     if (interrupt_request & CPU_INTERRUPT_HARD
 157         && ((env->sr & SR_I) >> SR_I_SHIFT) < env->pending_level) {
 158         /* Real hardware gets the interrupt vector via an IACK cycle
 159            at this point.  Current emulated hardware doesn't rely on
 160            this, so we provide/save the vector when the interrupt is
 161            first signalled.  */
 162         cs->exception_index = env->pending_vector;
 163         do_interrupt_m68k_hardirq(env);
 164         return true;
 165     }
 166     return false;
 167 }
 168
 169 static void raise_exception(CPUM68KState *env, int tt)
 170 {
 171     CPUState *cs = CPU(m68k_env_get_cpu(env));
 172
 173     cs->exception_index = tt;
 174     cpu_loop_exit(cs);
 175 }
 176
 177 void HELPER(raise_exception)(CPUM68KState *env, uint32_t tt)
 178 {
 179     raise_exception(env, tt);
 180 }
 181
 182 void HELPER(divu)(CPUM68KState *env, uint32_t word)
 183 {
 184     uint32_t num;
 185     uint32_t den;
 186     uint32_t quot;
 187     uint32_t rem;
 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
 198     env->cc_v = (word && quot > 0xffff ? -1 : 0);
 199     env->cc_z = quot;
 200     env->cc_n = quot;
 201     env->cc_c = 0;
 202
 203     env->div1 = quot;
 204     env->div2 = rem;
 205 }
 206
 207 void HELPER(divs)(CPUM68KState *env, uint32_t word)
 208 {
 209     int32_t num;
 210     int32_t den;
 211     int32_t quot;
 212     int32_t rem;
 213
 214     num = env->div1;
 215     den = env->div2;
 216     if (den == 0) {
 217         raise_exception(env, EXCP_DIV0);
 218     }
 219     quot = num / den;
 220     rem = num % den;
 221
 222     env->cc_v = (word && quot != (int16_t)quot ? -1 : 0);
 223     env->cc_z = quot;
 224     env->cc_n = quot;
 225     env->cc_c = 0;
 226
 227     env->div1 = quot;
 228     env->div2 = rem;
 229 }