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