target-sh4/helper.c

   1 /*
   2  *  SH4 emulation
   3  *
   4  *  Copyright (c) 2005 Samuel Tardieu
   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 <stdarg.h>
  20 #include <stdlib.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <inttypes.h>
  24 #include <signal.h>
  25
  26 #include "cpu.h"
  27 #include "exec-all.h"
  28 #include "hw/sh_intc.h"
  29
  30 #if defined(CONFIG_USER_ONLY)
  31
  32 void do_interrupt (CPUState *env)
  33 {
  34   env->exception_index = -1;
  35 }
  36
  37 int cpu_sh4_handle_mmu_fault(CPUState * env, target_ulong address, int rw,
  38                              int mmu_idx, int is_softmmu)
  39 {
  40     env->tea = address;
  41     env->exception_index = -1;
  42     switch (rw) {
  43     case 0:
  44         env->exception_index = 0x0a0;
  45         break;
  46     case 1:
  47         env->exception_index = 0x0c0;
  48         break;
  49     case 2:
  50         env->exception_index = 0x0a0;
  51         break;
  52     }
  53     return 1;
  54 }
  55
  56 int cpu_sh4_is_cached(CPUSH4State * env, target_ulong addr)
  57 {
  58     /* For user mode, only U0 area is cachable. */
  59     return !(addr & 0x80000000);
  60 }
  61
  62 #else /* !CONFIG_USER_ONLY */
  63
  64 #define MMU_OK                   0
  65 #define MMU_ITLB_MISS            (-1)
  66 #define MMU_ITLB_MULTIPLE        (-2)
  67 #define MMU_ITLB_VIOLATION       (-3)
  68 #define MMU_DTLB_MISS_READ       (-4)
  69 #define MMU_DTLB_MISS_WRITE      (-5)
  70 #define MMU_DTLB_INITIAL_WRITE   (-6)
  71 #define MMU_DTLB_VIOLATION_READ  (-7)
  72 #define MMU_DTLB_VIOLATION_WRITE (-8)
  73 #define MMU_DTLB_MULTIPLE        (-9)
  74 #define MMU_DTLB_MISS            (-10)
  75 #define MMU_IADDR_ERROR          (-11)
  76 #define MMU_DADDR_ERROR_READ     (-12)
  77 #define MMU_DADDR_ERROR_WRITE    (-13)
  78
  79 void do_interrupt(CPUState * env)
  80 {
  81     int do_irq = env->interrupt_request & CPU_INTERRUPT_HARD;
  82     int do_exp, irq_vector = env->exception_index;
  83
  84     /* prioritize exceptions over interrupts */
  85
  86     do_exp = env->exception_index != -1;
  87     do_irq = do_irq && (env->exception_index == -1);
  88
  89     if (env->sr & SR_BL) {
  90         if (do_exp && env->exception_index != 0x1e0) {
  91             env->exception_index = 0x000; /* masked exception -> reset */
  92         }
  93         if (do_irq && !env->intr_at_halt) {
  94             return; /* masked */
  95         }
  96         env->intr_at_halt = 0;
  97     }
  98
  99     if (do_irq) {
 100         irq_vector = sh_intc_get_pending_vector(env->intc_handle,
 101                                                 (env->sr >> 4) & 0xf);
 102         if (irq_vector == -1) {
 103             return; /* masked */
 104         }
 105     }
 106
 107     if (qemu_loglevel_mask(CPU_LOG_INT)) {
 108         const char *expname;
 109         switch (env->exception_index) {
 110         case 0x0e0:
 111             expname = "addr_error";
 112             break;
 113         case 0x040:
 114             expname = "tlb_miss";
 115             break;
 116         case 0x0a0:
 117             expname = "tlb_violation";
 118             break;
 119         case 0x180:
 120             expname = "illegal_instruction";
 121             break;
 122         case 0x1a0:
 123             expname = "slot_illegal_instruction";
 124             break;
 125         case 0x800:
 126             expname = "fpu_disable";
 127             break;
 128         case 0x820:
 129             expname = "slot_fpu";
 130             break;
 131         case 0x100:
 132             expname = "data_write";
 133             break;
 134         case 0x060:
 135             expname = "dtlb_miss_write";
 136             break;
 137         case 0x0c0:
 138             expname = "dtlb_violation_write";
 139             break;
 140         case 0x120:
 141             expname = "fpu_exception";
 142             break;
 143         case 0x080:
 144             expname = "initial_page_write";
 145             break;
 146         case 0x160:
 147             expname = "trapa";
 148             break;
 149         default:
 150             expname = do_irq ? "interrupt" : "???";
 151             break;
 152         }
 153         qemu_log("exception 0x%03x [%s] raised\n",
 154                   irq_vector, expname);
 155         log_cpu_state(env, 0);
 156     }
 157
 158     env->ssr = env->sr;
 159     env->spc = env->pc;
 160     env->sgr = env->gregs[15];
 161     env->sr |= SR_BL | SR_MD | SR_RB;
 162
 163     if (env->flags & (DELAY_SLOT | DELAY_SLOT_CONDITIONAL)) {
 164         /* Branch instruction should be executed again before delay slot. */
 165         env->spc -= 2;
 166         /* Clear flags for exception/interrupt routine. */
 167         env->flags &= ~(DELAY_SLOT | DELAY_SLOT_CONDITIONAL | DELAY_SLOT_TRUE);
 168     }
 169     if (env->flags & DELAY_SLOT_CLEARME)
 170         env->flags = 0;
 171
 172     if (do_exp) {
 173         env->expevt = env->exception_index;
 174         switch (env->exception_index) {
 175         case 0x000:
 176         case 0x020:
 177         case 0x140:
 178             env->sr &= ~SR_FD;
 179             env->sr |= 0xf << 4; /* IMASK */
 180             env->pc = 0xa0000000;
 181             break;
 182         case 0x040:
 183         case 0x060:
 184             env->pc = env->vbr + 0x400;
 185             break;
 186         case 0x160:
 187             env->spc += 2; /* special case for TRAPA */
 188             /* fall through */
 189         default:
 190             env->pc = env->vbr + 0x100;
 191             break;
 192         }
 193         return;
 194     }
 195
 196     if (do_irq) {
 197         env->intevt = irq_vector;
 198         env->pc = env->vbr + 0x600;
 199         return;
 200     }
 201 }
 202
 203 static void update_itlb_use(CPUState * env, int itlbnb)
 204 {
 205     uint8_t or_mask = 0, and_mask = (uint8_t) - 1;
 206
 207     switch (itlbnb) {
 208     case 0:
 209         and_mask = 0x1f;
 210         break;
 211     case 1:
 212         and_mask = 0xe7;
 213         or_mask = 0x80;
 214         break;
 215     case 2:
 216         and_mask = 0xfb;
 217         or_mask = 0x50;
 218         break;
 219     case 3:
 220         or_mask = 0x2c;
 221         break;
 222     }
 223
 224     env->mmucr &= (and_mask << 24) | 0x00ffffff;
 225     env->mmucr |= (or_mask << 24);
 226 }
 227
 228 static int itlb_replacement(CPUState * env)
 229 {
 230     if ((env->mmucr & 0xe0000000) == 0xe0000000)
 231         return 0;
 232     if ((env->mmucr & 0x98000000) == 0x18000000)
 233         return 1;
 234     if ((env->mmucr & 0x54000000) == 0x04000000)
 235         return 2;
 236     if ((env->mmucr & 0x2c000000) == 0x00000000)
 237         return 3;
 238     cpu_abort(env, "Unhandled itlb_replacement");
 239 }
 240
 241 /* Find the corresponding entry in the right TLB
 242    Return entry, MMU_DTLB_MISS or MMU_DTLB_MULTIPLE
 243 */
 244 static int find_tlb_entry(CPUState * env, target_ulong address,
 245                           tlb_t * entries, uint8_t nbtlb, int use_asid)
 246 {
 247     int match = MMU_DTLB_MISS;
 248     uint32_t start, end;
 249     uint8_t asid;
 250     int i;
 251
 252     asid = env->pteh & 0xff;
 253
 254     for (i = 0; i < nbtlb; i++) {
 255         if (!entries[i].v)
 256             continue;           /* Invalid entry */
 257         if (!entries[i].sh && use_asid && entries[i].asid != asid)
 258             continue;           /* Bad ASID */
 259         start = (entries[i].vpn << 10) & ~(entries[i].size - 1);
 260         end = start + entries[i].size - 1;
 261         if (address >= start && address <= end) {       /* Match */
 262             if (match != MMU_DTLB_MISS)
 263                 return MMU_DTLB_MULTIPLE;       /* Multiple match */
 264             match = i;
 265         }
 266     }
 267     return match;
 268 }
 269
 270 static void increment_urc(CPUState * env)
 271 {
 272     uint8_t urb, urc;
 273
 274     /* Increment URC */
 275     urb = ((env->mmucr) >> 18) & 0x3f;
 276     urc = ((env->mmucr) >> 10) & 0x3f;
 277     urc++;
 278     if ((urb > 0 && urc > urb) || urc > (UTLB_SIZE - 1))
 279         urc = 0;
 280     env->mmucr = (env->mmucr & 0xffff03ff) | (urc << 10);
 281 }
 282
 283 /* Find itlb entry - update itlb from utlb if necessary and asked for
 284    Return entry, MMU_ITLB_MISS, MMU_ITLB_MULTIPLE or MMU_DTLB_MULTIPLE
 285    Update the itlb from utlb if update is not 0
 286 */
 287 static int find_itlb_entry(CPUState * env, target_ulong address,
 288                            int use_asid, int update)
 289 {
 290     int e, n;
 291
 292     e = find_tlb_entry(env, address, env->itlb, ITLB_SIZE, use_asid);
 293     if (e == MMU_DTLB_MULTIPLE)
 294         e = MMU_ITLB_MULTIPLE;
 295     else if (e == MMU_DTLB_MISS && update) {
 296         e = find_tlb_entry(env, address, env->utlb, UTLB_SIZE, use_asid);
 297         if (e >= 0) {
 298             tlb_t * ientry;
 299             n = itlb_replacement(env);
 300             ientry = &env->itlb[n];
 301             if (ientry->v) {
 302                 tlb_flush_page(env, ientry->vpn << 10);
 303             }
 304             *ientry = env->utlb[e];
 305             e = n;
 306         } else if (e == MMU_DTLB_MISS)
 307             e = MMU_ITLB_MISS;
 308     } else if (e == MMU_DTLB_MISS)
 309         e = MMU_ITLB_MISS;
 310     if (e >= 0)
 311         update_itlb_use(env, e);
 312     return e;
 313 }
 314
 315 /* Find utlb entry
 316    Return entry, MMU_DTLB_MISS, MMU_DTLB_MULTIPLE */
 317 static int find_utlb_entry(CPUState * env, target_ulong address, int use_asid)
 318 {
 319     /* per utlb access */
 320     increment_urc(env);
 321
 322     /* Return entry */
 323     return find_tlb_entry(env, address, env->utlb, UTLB_SIZE, use_asid);
 324 }
 325
 326 /* Match address against MMU
 327    Return MMU_OK, MMU_DTLB_MISS_READ, MMU_DTLB_MISS_WRITE,
 328    MMU_DTLB_INITIAL_WRITE, MMU_DTLB_VIOLATION_READ,
 329    MMU_DTLB_VIOLATION_WRITE, MMU_ITLB_MISS,
 330    MMU_ITLB_MULTIPLE, MMU_ITLB_VIOLATION,
 331    MMU_IADDR_ERROR, MMU_DADDR_ERROR_READ, MMU_DADDR_ERROR_WRITE.
 332 */
 333 static int get_mmu_address(CPUState * env, target_ulong * physical,
 334                            int *prot, target_ulong address,
 335                            int rw, int access_type)
 336 {
 337     int use_asid, n;
 338     tlb_t *matching = NULL;
 339
 340     use_asid = (env->mmucr & MMUCR_SV) == 0 || (env->sr & SR_MD) == 0;
 341
 342     if (rw == 2) {
 343         n = find_itlb_entry(env, address, use_asid, 1);
 344         if (n >= 0) {
 345             matching = &env->itlb[n];
 346             if (!(env->sr & SR_MD) && !(matching->pr & 2))
 347                 n = MMU_ITLB_VIOLATION;
 348             else
 349                 *prot = PAGE_EXEC;
 350         }
 351     } else {
 352         n = find_utlb_entry(env, address, use_asid);
 353         if (n >= 0) {
 354             matching = &env->utlb[n];
 355             if (!(env->sr & SR_MD) && !(matching->pr & 2)) {
 356                 n = (rw == 1) ? MMU_DTLB_VIOLATION_WRITE :
 357                     MMU_DTLB_VIOLATION_READ;
 358             } else if ((rw == 1) && !(matching->pr & 1)) {
 359                 n = MMU_DTLB_VIOLATION_WRITE;
 360             } else if ((rw == 1) & !matching->d) {
 361                 n = MMU_DTLB_INITIAL_WRITE;
 362             } else {
 363                 *prot = PAGE_READ;
 364                 if ((matching->pr & 1) && matching->d) {
 365                     *prot |= PAGE_WRITE;
 366                 }
 367             }
 368         } else if (n == MMU_DTLB_MISS) {
 369             n = (rw == 1) ? MMU_DTLB_MISS_WRITE :
 370                 MMU_DTLB_MISS_READ;
 371         }
 372     }
 373     if (n >= 0) {
 374         n = MMU_OK;
 375         *physical = ((matching->ppn << 10) & ~(matching->size - 1)) |
 376             (address & (matching->size - 1));
 377     }
 378     return n;
 379 }
 380
 381 static int get_physical_address(CPUState * env, target_ulong * physical,
 382                                 int *prot, target_ulong address,
 383                                 int rw, int access_type)
 384 {
 385     /* P1, P2 and P4 areas do not use translation */
 386     if ((address >= 0x80000000 && address < 0xc0000000) ||
 387         address >= 0xe0000000) {
 388         if (!(env->sr & SR_MD)
 389             && (address < 0xe0000000 || address >= 0xe4000000)) {
 390             /* Unauthorized access in user mode (only store queues are available) */
 391             fprintf(stderr, "Unauthorized access\n");
 392             if (rw == 0)
 393                 return MMU_DADDR_ERROR_READ;
 394             else if (rw == 1)
 395                 return MMU_DADDR_ERROR_WRITE;
 396             else
 397                 return MMU_IADDR_ERROR;
 398         }
 399         if (address >= 0x80000000 && address < 0xc0000000) {
 400             /* Mask upper 3 bits for P1 and P2 areas */
 401             *physical = address & 0x1fffffff;
 402         } else {
 403             *physical = address;
 404         }
 405         *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
 406         return MMU_OK;
 407     }
 408
 409     /* If MMU is disabled, return the corresponding physical page */
 410     if (!env->mmucr & MMUCR_AT) {
 411         *physical = address & 0x1FFFFFFF;
 412         *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
 413         return MMU_OK;
 414     }
 415
 416     /* We need to resort to the MMU */
 417     return get_mmu_address(env, physical, prot, address, rw, access_type);
 418 }
 419
 420 int cpu_sh4_handle_mmu_fault(CPUState * env, target_ulong address, int rw,
 421                              int mmu_idx, int is_softmmu)
 422 {
 423     target_ulong physical;
 424     int prot, ret, access_type;
 425
 426     access_type = ACCESS_INT;
 427     ret =
 428         get_physical_address(env, &physical, &prot, address, rw,
 429                              access_type);
 430
 431     if (ret != MMU_OK) {
 432         env->tea = address;
 433         switch (ret) {
 434         case MMU_ITLB_MISS:
 435         case MMU_DTLB_MISS_READ:
 436             env->exception_index = 0x040;
 437             break;
 438         case MMU_DTLB_MULTIPLE:
 439         case MMU_ITLB_MULTIPLE:
 440             env->exception_index = 0x140;
 441             break;
 442         case MMU_ITLB_VIOLATION:
 443             env->exception_index = 0x0a0;
 444             break;
 445         case MMU_DTLB_MISS_WRITE:
 446             env->exception_index = 0x060;
 447             break;
 448         case MMU_DTLB_INITIAL_WRITE:
 449             env->exception_index = 0x080;
 450             break;
 451         case MMU_DTLB_VIOLATION_READ:
 452             env->exception_index = 0x0a0;
 453             break;
 454         case MMU_DTLB_VIOLATION_WRITE:
 455             env->exception_index = 0x0c0;
 456             break;
 457         case MMU_IADDR_ERROR:
 458         case MMU_DADDR_ERROR_READ:
 459             env->exception_index = 0x0c0;
 460             break;
 461         case MMU_DADDR_ERROR_WRITE:
 462             env->exception_index = 0x100;
 463             break;
 464         default:
 465             cpu_abort(env, "Unhandled MMU fault");
 466         }
 467         return 1;
 468     }
 469
 470     address &= TARGET_PAGE_MASK;
 471     physical &= TARGET_PAGE_MASK;
 472
 473     tlb_set_page(env, address, physical, prot, mmu_idx, TARGET_PAGE_SIZE);
 474     return 0;
 475 }
 476
 477 target_phys_addr_t cpu_get_phys_page_debug(CPUState * env, target_ulong addr)
 478 {
 479     target_ulong physical;
 480     int prot;
 481
 482     get_physical_address(env, &physical, &prot, addr, 0, 0);
 483     return physical;
 484 }
 485
 486 void cpu_load_tlb(CPUSH4State * env)
 487 {
 488     int n = cpu_mmucr_urc(env->mmucr);
 489     tlb_t * entry = &env->utlb[n];
 490
 491     if (entry->v) {
 492         /* Overwriting valid entry in utlb. */
 493         target_ulong address = entry->vpn << 10;
 494         tlb_flush_page(env, address);
 495     }
 496
 497     /* Take values into cpu status from registers. */
 498     entry->asid = (uint8_t)cpu_pteh_asid(env->pteh);
 499     entry->vpn  = cpu_pteh_vpn(env->pteh);
 500     entry->v    = (uint8_t)cpu_ptel_v(env->ptel);
 501     entry->ppn  = cpu_ptel_ppn(env->ptel);
 502     entry->sz   = (uint8_t)cpu_ptel_sz(env->ptel);
 503     switch (entry->sz) {
 504     case 0: /* 00 */
 505         entry->size = 1024; /* 1K */
 506         break;
 507     case 1: /* 01 */
 508         entry->size = 1024 * 4; /* 4K */
 509         break;
 510     case 2: /* 10 */
 511         entry->size = 1024 * 64; /* 64K */
 512         break;
 513     case 3: /* 11 */
 514         entry->size = 1024 * 1024; /* 1M */
 515         break;
 516     default:
 517         cpu_abort(env, "Unhandled load_tlb");
 518         break;
 519     }
 520     entry->sh   = (uint8_t)cpu_ptel_sh(env->ptel);
 521     entry->c    = (uint8_t)cpu_ptel_c(env->ptel);
 522     entry->pr   = (uint8_t)cpu_ptel_pr(env->ptel);
 523     entry->d    = (uint8_t)cpu_ptel_d(env->ptel);
 524     entry->wt   = (uint8_t)cpu_ptel_wt(env->ptel);
 525     entry->sa   = (uint8_t)cpu_ptea_sa(env->ptea);
 526     entry->tc   = (uint8_t)cpu_ptea_tc(env->ptea);
 527 }
 528
 529  void cpu_sh4_invalidate_tlb(CPUSH4State *s)
 530 {
 531     int i;
 532
 533     /* UTLB */
 534     for (i = 0; i < UTLB_SIZE; i++) {
 535         tlb_t * entry = &s->utlb[i];
 536         entry->v = 0;
 537     }
 538     /* ITLB */
 539     for (i = 0; i < UTLB_SIZE; i++) {
 540         tlb_t * entry = &s->utlb[i];
 541         entry->v = 0;
 542     }
 543
 544     tlb_flush(s, 1);
 545 }
 546
 547 void cpu_sh4_write_mmaped_utlb_addr(CPUSH4State *s, target_phys_addr_t addr,
 548                                     uint32_t mem_value)
 549 {
 550     int associate = addr & 0x0000080;
 551     uint32_t vpn = (mem_value & 0xfffffc00) >> 10;
 552     uint8_t d = (uint8_t)((mem_value & 0x00000200) >> 9);
 553     uint8_t v = (uint8_t)((mem_value & 0x00000100) >> 8);
 554     uint8_t asid = (uint8_t)(mem_value & 0x000000ff);
 555     int use_asid = (s->mmucr & MMUCR_SV) == 0 || (s->sr & SR_MD) == 0;
 556
 557     if (associate) {
 558         int i;
 559         tlb_t * utlb_match_entry = NULL;
 560         int needs_tlb_flush = 0;
 561
 562         /* search UTLB */
 563         for (i = 0; i < UTLB_SIZE; i++) {
 564             tlb_t * entry = &s->utlb[i];
 565             if (!entry->v)
 566                 continue;
 567
 568             if (entry->vpn == vpn
 569                 && (!use_asid || entry->asid == asid || entry->sh)) {
 570                 if (utlb_match_entry) {
 571                     /* Multiple TLB Exception */
 572                     s->exception_index = 0x140;
 573                     s->tea = addr;
 574                     break;
 575                 }
 576                 if (entry->v && !v)
 577                     needs_tlb_flush = 1;
 578                 entry->v = v;
 579                 entry->d = d;
 580                 utlb_match_entry = entry;
 581             }
 582             increment_urc(s); /* per utlb access */
 583         }
 584
 585         /* search ITLB */
 586         for (i = 0; i < ITLB_SIZE; i++) {
 587             tlb_t * entry = &s->itlb[i];
 588             if (entry->vpn == vpn
 589                 && (!use_asid || entry->asid == asid || entry->sh)) {
 590                 if (entry->v && !v)
 591                     needs_tlb_flush = 1;
 592                 if (utlb_match_entry)
 593                     *entry = *utlb_match_entry;
 594                 else
 595                     entry->v = v;
 596                 break;
 597             }
 598         }
 599
 600         if (needs_tlb_flush)
 601             tlb_flush_page(s, vpn << 10);
 602
 603     } else {
 604         int index = (addr & 0x00003f00) >> 8;
 605         tlb_t * entry = &s->utlb[index];
 606         if (entry->v) {
 607             /* Overwriting valid entry in utlb. */
 608             target_ulong address = entry->vpn << 10;
 609             tlb_flush_page(s, address);
 610         }
 611         entry->asid = asid;
 612         entry->vpn = vpn;
 613         entry->d = d;
 614         entry->v = v;
 615         increment_urc(s);
 616     }
 617 }
 618
 619 int cpu_sh4_is_cached(CPUSH4State * env, target_ulong addr)
 620 {
 621     int n;
 622     int use_asid = (env->mmucr & MMUCR_SV) == 0 || (env->sr & SR_MD) == 0;
 623
 624     /* check area */
 625     if (env->sr & SR_MD) {
 626         /* For previledged mode, P2 and P4 area is not cachable. */
 627         if ((0xA0000000 <= addr && addr < 0xC0000000) || 0xE0000000 <= addr)
 628             return 0;
 629     } else {
 630         /* For user mode, only U0 area is cachable. */
 631         if (0x80000000 <= addr)
 632             return 0;
 633     }
 634
 635     /*
 636      * TODO : Evaluate CCR and check if the cache is on or off.
 637      *        Now CCR is not in CPUSH4State, but in SH7750State.
 638      *        When you move the ccr inot CPUSH4State, the code will be
 639      *        as follows.
 640      */
 641 #if 0
 642     /* check if operand cache is enabled or not. */
 643     if (!(env->ccr & 1))
 644         return 0;
 645 #endif
 646
 647     /* if MMU is off, no check for TLB. */
 648     if (env->mmucr & MMUCR_AT)
 649         return 1;
 650
 651     /* check TLB */
 652     n = find_tlb_entry(env, addr, env->itlb, ITLB_SIZE, use_asid);
 653     if (n >= 0)
 654         return env->itlb[n].c;
 655
 656     n = find_tlb_entry(env, addr, env->utlb, UTLB_SIZE, use_asid);
 657     if (n >= 0)
 658         return env->utlb[n].c;
 659
 660     return 0;
 661 }
 662
 663 #endif