target/nios2/op_helper.c

   1 /*
   2  * Altera Nios II helper routines.
   3  *
   4  * Copyright (C) 2012 Chris Wulff <crwulff@gmail.com>
   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 2.1 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
  18  * <http://www.gnu.org/licenses/lgpl-2.1.html>
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "cpu.h"
  23 #include "exec/helper-proto.h"
  24 #include "exec/exec-all.h"
  25 #include "qemu/main-loop.h"
  26
  27 void helper_raise_exception(CPUNios2State *env, uint32_t index)
  28 {
  29     CPUState *cs = env_cpu(env);
  30     cs->exception_index = index;
  31     cpu_loop_exit(cs);
  32 }
  33
  34 void nios2_cpu_loop_exit_advance(CPUNios2State *env, uintptr_t retaddr)
  35 {
  36     CPUState *cs = env_cpu(env);
  37
  38     /*
  39      * Note that PC is advanced for all hardware exceptions.
  40      * Do this here, rather than in restore_state_to_opc(),
  41      * lest we affect QEMU internal exceptions, like EXCP_DEBUG.
  42      */
  43     cpu_restore_state(cs, retaddr);
  44     env->pc += 4;
  45     cpu_loop_exit(cs);
  46 }
  47
  48 static void maybe_raise_div(CPUNios2State *env, uintptr_t ra)
  49 {
  50     Nios2CPU *cpu = env_archcpu(env);
  51     CPUState *cs = env_cpu(env);
  52
  53     if (cpu->diverr_present) {
  54         cs->exception_index = EXCP_DIV;
  55         nios2_cpu_loop_exit_advance(env, ra);
  56     }
  57 }
  58
  59 int32_t helper_divs(CPUNios2State *env, int32_t num, int32_t den)
  60 {
  61     if (unlikely(den == 0) || unlikely(den == -1 && num == INT32_MIN)) {
  62         maybe_raise_div(env, GETPC());
  63         return num; /* undefined */
  64     }
  65     return num / den;
  66 }
  67
  68 uint32_t helper_divu(CPUNios2State *env, uint32_t num, uint32_t den)
  69 {
  70     if (unlikely(den == 0)) {
  71         maybe_raise_div(env, GETPC());
  72         return num; /* undefined */
  73     }
  74     return num / den;
  75 }
  76
  77 #ifndef CONFIG_USER_ONLY
  78 void helper_eret(CPUNios2State *env, uint32_t new_status, uint32_t new_pc)
  79 {
  80     Nios2CPU *cpu = env_archcpu(env);
  81     CPUState *cs = env_cpu(env);
  82
  83     if (unlikely(new_pc & 3)) {
  84         env->ctrl[CR_BADADDR] = new_pc;
  85         cs->exception_index = EXCP_UNALIGND;
  86         nios2_cpu_loop_exit_advance(env, GETPC());
  87     }
  88
  89     /*
  90      * None of estatus, bstatus, or sstatus have constraints on write;
  91      * do not allow reserved fields in status to be set.
  92      * When shadow registers are enabled, eret *does* restore CRS.
  93      * Rather than testing eic_present to decide, mask CRS out of
  94      * the set of readonly fields.
  95      */
  96     new_status &= cpu->cr_state[CR_STATUS].writable |
  97                   (cpu->cr_state[CR_STATUS].readonly & R_CR_STATUS_CRS_MASK);
  98
  99     env->ctrl[CR_STATUS] = new_status;
 100     env->pc = new_pc;
 101     nios2_update_crs(env);
 102     cpu_loop_exit(cs);
 103 }
 104
 105 /*
 106  * RDPRS and WRPRS are implemented out of line so that if PRS == CRS,
 107  * all of the tcg global temporaries are synced back to ENV.
 108  */
 109 uint32_t helper_rdprs(CPUNios2State *env, uint32_t regno)
 110 {
 111     unsigned prs = FIELD_EX32(env->ctrl[CR_STATUS], CR_STATUS, PRS);
 112     return env->shadow_regs[prs][regno];
 113 }
 114
 115 void helper_wrprs(CPUNios2State *env, uint32_t regno, uint32_t val)
 116 {
 117     unsigned prs = FIELD_EX32(env->ctrl[CR_STATUS], CR_STATUS, PRS);
 118     env->shadow_regs[prs][regno] = val;
 119 }
 120 #endif /* !CONFIG_USER_ONLY */