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 target_phys_addr_t cpu_get_phys_page_debug(CPUState * env, target_ulong addr)
  57 {
  58     return addr;
  59 }
  60
  61 int cpu_sh4_is_cached(CPUSH4State * env, target_ulong addr)
  62 {
  63     /* For user mode, only U0 area is cachable. */
  64     return !(addr & 0x80000000);
  65 }
  66
  67 #else /* !CONFIG_USER_ONLY */
  68
  69 #define MMU_OK                   0
  70 #define MMU_ITLB_MISS            (-1)
  71 #define MMU_ITLB_MULTIPLE        (-2)
  72 #define MMU_ITLB_VIOLATION       (-3)
  73 #define MMU_DTLB_MISS_READ       (-4)
  74 #define MMU_DTLB_MISS_WRITE      (-5)
  75 #define MMU_DTLB_INITIAL_WRITE   (-6)
  76 #define MMU_DTLB_VIOLATION_READ  (-7)
  77 #define MMU_DTLB_VIOLATION_WRITE (-8)
  78 #define MMU_DTLB_MULTIPLE        (-9)
  79 #define MMU_DTLB_MISS            (-10)
  80 #define MMU_IADDR_ERROR          (-11)
  81 #define MMU_DADDR_ERROR_READ     (-12)
  82 #define MMU_DADDR_ERROR_WRITE    (-13)
  83
  84 void do_interrupt(CPUState * env)
  85 {
  86     int do_irq = env->interrupt_request & CPU_INTERRUPT_HARD;
  87     int do_exp, irq_vector = env->exception_index;
  88
  89     /* prioritize exceptions over interrupts */
  90
  91     do_exp = env->exception_index != -1;
  92     do_irq = do_irq && (env->exception_index == -1);
  93
  94     if (env->sr & SR_BL) {
  95         if (do_exp && env->exception_index != 0x1e0) {
  96             env->exception_index = 0x000; /* masked exception -> reset */
  97         }
  98         if (do_irq && !env->intr_at_halt) {
  99             return; /* masked */
 100         }
 101         env->intr_at_halt = 0;
 102     }
 103
 104     if (do_irq) {
 105         irq_vector = sh_intc_get_pending_vector(env->intc_handle,
 106                                                 (env->sr >> 4) & 0xf);
 107         if (irq_vector == -1) {
 108             return; /* masked */
 109         }
 110     }
 111
 112     if (qemu_loglevel_mask(CPU_LOG_INT)) {
 113         const char *expname;
 114         switch (env->exception_index) {
 115         case 0x0e0:
 116             expname = "addr_error";
 117             break;
 118         case 0x040:
 119             expname = "tlb_miss";
 120             break;
 121         case 0x0a0:
 122             expname = "tlb_violation";
 123             break;
 124         case 0x180:
 125             expname = "illegal_instruction";
 126             break;
 127         case 0x1a0:
 128             expname = "slot_illegal_instruction";
 129             break;
 130         case 0x800:
 131             expname = "fpu_disable";
 132             break;
 133         case 0x820:
 134             expname = "slot_fpu";
 135             break;
 136         case 0x100:
 137             expname = "data_write";
 138             break;
 139         case 0x060:
 140             expname = "dtlb_miss_write";
 141             break;
 142         case 0x0c0:
 143             expname = "dtlb_violation_write";
 144             break;
 145         case 0x120:
 146             expname = "fpu_exception";
 147             break;
 148         case 0x080:
 149             expname = "initial_page_write";
 150             break;
 151         case 0x160:
 152             expname = "trapa";
 153             break;
 154         default:
 155             expname = do_irq ? "interrupt" : "???";
 156             break;
 157         }
 158         qemu_log("exception 0x%03x [%s] raised\n",
 159                   irq_vector, expname);
 160         log_cpu_state(env, 0);
 161     }
 162
 163     env->ssr = env->sr;
 164     env->spc = env->pc;
 165     env->sgr = env->gregs[15];
 166     env->sr |= SR_BL | SR_MD | SR_RB;
 167
 168     if (env->flags & (DELAY_SLOT | DELAY_SLOT_CONDITIONAL)) {
 169         /* Branch instruction should be executed again before delay slot. */
 170         env->spc -= 2;
 171         /* Clear flags for exception/interrupt routine. */
 172         env->flags &= ~(DELAY_SLOT | DELAY_SLOT_CONDITIONAL | DELAY_SLOT_TRUE);
 173     }
 174     if (env->flags & DELAY_SLOT_CLEARME)
 175         env->flags = 0;
 176
 177     if (do_exp) {
 178         env->expevt = env->exception_index;
 179         switch (env->exception_index) {
 180         case 0x000:
 181         case 0x020:
 182         case 0x140:
 183             env->sr &= ~SR_FD;
 184             env->sr |= 0xf << 4; /* IMASK */
 185             env->pc = 0xa0000000;
 186             break;
 187         case 0x040:
 188         case 0x060:
 189             env->pc = env->vbr + 0x400;
 190             break;
 191         case 0x160:
 192             env->spc += 2; /* special case for TRAPA */
 193             /* fall through */
 194         default:
 195             env->pc = env->vbr + 0x100;
 196             break;
 197         }
 198         return;
 199     }
 200
 201     if (do_irq) {
 202         env->intevt = irq_vector;
 203         env->pc = env->vbr + 0x600;
 204         return;
 205     }
 206 }
 207
 208 static void update_itlb_use(CPUState * env, int itlbnb)
 209 {
 210     uint8_t or_mask = 0, and_mask = (uint8_t) - 1;
 211
 212     switch (itlbnb) {
 213     case 0:
 214         and_mask = 0x1f;
 215         break;
 216     case 1:
 217         and_mask = 0xe7;
 218         or_mask = 0x80;
 219         break;
 220     case 2:
 221         and_mask = 0xfb;
 222         or_mask = 0x50;
 223         break;
 224     case 3:
 225         or_mask = 0x2c;
 226         break;
 227     }
 228
 229     env->mmucr &= (and_mask << 24) | 0x00ffffff;
 230     env->mmucr |= (or_mask << 24);
 231 }
 232
 233 static int itlb_replacement(CPUState * env)
 234 {
 235     if ((env->mmucr & 0xe0000000) == 0xe0000000)
 236         return 0;
 237     if ((env->mmucr & 0x98000000) == 0x18000000)
 238         return 1;
 239     if ((env->mmucr & 0x54000000) == 0x04000000)
 240         return 2;
 241     if ((env->mmucr & 0x2c000000) == 0x00000000)
 242         return 3;
 243     assert(0);
 244 }
 245
 246 /* Find the corresponding entry in the right TLB
 247    Return entry, MMU_DTLB_MISS or MMU_DTLB_MULTIPLE
 248 */
 249 static int find_tlb_entry(CPUState * env, target_ulong address,
 250                           tlb_t * entries, uint8_t nbtlb, int use_asid)
 251 {
 252     int match = MMU_DTLB_MISS;
 253     uint32_t start, end;
 254     uint8_t asid;
 255     int i;
 256
 257     asid = env->pteh & 0xff;
 258
 259     for (i = 0; i < nbtlb; i++) {
 260         if (!entries[i].v)
 261             continue;           /* Invalid entry */
 262         if (!entries[i].sh && use_asid && entries[i].asid != asid)
 263             continue;           /* Bad ASID */
 264         start = (entries[i].vpn << 10) & ~(entries[i].size - 1);
 265         end = start + entries[i].size - 1;
 266         if (address >= start && address <= end) {       /* Match */
 267             if (match != MMU_DTLB_MISS)
 268                 return MMU_DTLB_MULTIPLE;       /* Multiple match */
 269             match = i;
 270         }
 271     }
 272     return match;
 273 }
 274
 275 static void increment_urc(CPUState * env)
 276 {
 277     uint8_t urb, urc;
 278
 279     /* Increment URC */
 280     urb = ((env->mmucr) >> 18) & 0x3f;
 281     urc = ((env->mmucr) >> 10) & 0x3f;
 282     urc++;
 283     if ((urb > 0 && urc > urb) || urc > (UTLB_SIZE - 1))
 284         urc = 0;
 285     env->mmucr = (env->mmucr & 0xffff03ff) | (urc << 10);
 286 }
 287
 288 /* Find itlb entry - update itlb from utlb if necessary and asked for
 289    Return entry, MMU_ITLB_MISS, MMU_ITLB_MULTIPLE or MMU_DTLB_MULTIPLE
 290    Update the itlb from utlb if update is not 0
 291 */
 292 static int find_itlb_entry(CPUState * env, target_ulong address,
 293                            int use_asid, int update)
 294 {
 295     int e, n;
 296
 297     e = find_tlb_entry(env, address, env->itlb, ITLB_SIZE, use_asid);
 298     if (e == MMU_DTLB_MULTIPLE)
 299         e = MMU_ITLB_MULTIPLE;
 300     else if (e == MMU_DTLB_MISS && update) {
 301         e = find_tlb_entry(env, address, env->utlb, UTLB_SIZE, use_asid);
 302         if (e >= 0) {
 303             tlb_t * ientry;
 304             n = itlb_replacement(env);
 305             ientry = &env->itlb[n];
 306             if (ientry->v) {
 307                 tlb_flush_page(env, ientry->vpn << 10);
 308             }
 309             *ientry = env->utlb[e];
 310             e = n;
 311         } else if (e == MMU_DTLB_MISS)
 312             e = MMU_ITLB_MISS;
 313     } else if (e == MMU_DTLB_MISS)
 314         e = MMU_ITLB_MISS;
 315     if (e >= 0)
 316         update_itlb_use(env, e);
 317     return e;
 318 }
 319
 320 /* Find utlb entry
 321    Return entry, MMU_DTLB_MISS, MMU_DTLB_MULTIPLE */
 322 static int find_utlb_entry(CPUState * env, target_ulong address, int use_asid)
 323 {
 324     /* per utlb access */
 325     increment_urc(env);
 326
 327     /* Return entry */
 328     return find_tlb_entry(env, address, env->utlb, UTLB_SIZE, use_asid);
 329 }
 330
 331 /* Match address against MMU
 332    Return MMU_OK, MMU_DTLB_MISS_READ, MMU_DTLB_MISS_WRITE,
 333    MMU_DTLB_INITIAL_WRITE, MMU_DTLB_VIOLATION_READ,
 334    MMU_DTLB_VIOLATION_WRITE, MMU_ITLB_MISS,
 335    MMU_ITLB_MULTIPLE, MMU_ITLB_VIOLATION,
 336    MMU_IADDR_ERROR, MMU_DADDR_ERROR_READ, MMU_DADDR_ERROR_WRITE.
 337 */
 338 static int get_mmu_address(CPUState * env, target_ulong * physical,
 339                            int *prot, target_ulong address,
 340                            int rw, int access_type)
 341 {
 342     int use_asid, n;
 343     tlb_t *matching = NULL;
 344
 345     use_asid = (env->mmucr & MMUCR_SV) == 0 || (env->sr & SR_MD) == 0;
 346
 347     if (rw == 2) {
 348         n = find_itlb_entry(env, address, use_asid, 1);
 349         if (n >= 0) {
 350             matching = &env->itlb[n];
 351             if (!(env->sr & SR_MD) && !(matching->pr & 2))
 352                 n = MMU_ITLB_VIOLATION;
 353             else
 354                 *prot = PAGE_EXEC;
 355         }
 356     } else {
 357         n = find_utlb_entry(env, address, use_asid);
 358         if (n >= 0) {
 359             matching = &env->utlb[n];
 360             if (!(env->sr & SR_MD) && !(matching->pr & 2)) {
 361                 n = (rw == 1) ? MMU_DTLB_VIOLATION_WRITE :
 362                     MMU_DTLB_VIOLATION_READ;
 363             } else if ((rw == 1) && !(matching->pr & 1)) {
 364                 n = MMU_DTLB_VIOLATION_WRITE;
 365             } else if ((rw == 1) & !matching->d) {
 366                 n = MMU_DTLB_INITIAL_WRITE;
 367             } else {
 368                 *prot = PAGE_READ;
 369                 if ((matching->pr & 1) && matching->d) {
 370                     *prot |= PAGE_WRITE;
 371                 }
 372             }
 373         } else if (n == MMU_DTLB_MISS) {
 374             n = (rw == 1) ? MMU_DTLB_MISS_WRITE :
 375                 MMU_DTLB_MISS_READ;
 376         }
 377     }
 378     if (n >= 0) {
 379         n = MMU_OK;
 380         *physical = ((matching->ppn << 10) & ~(matching->size - 1)) |
 381             (address & (matching->size - 1));
 382     }
 383     return n;
 384 }
 385
 386 static int get_physical_address(CPUState * env, target_ulong * physical,
 387                                 int *prot, target_ulong address,
 388                                 int rw, int access_type)
 389 {
 390     /* P1, P2 and P4 areas do not use translation */
 391     if ((address >= 0x80000000 && address < 0xc0000000) ||
 392         address >= 0xe0000000) {
 393         if (!(env->sr & SR_MD)
 394             && (address < 0xe0000000 || address >= 0xe4000000)) {
 395             /* Unauthorized access in user mode (only store queues are available) */
 396             fprintf(stderr, "Unauthorized access\n");
 397             if (rw == 0)
 398                 return MMU_DADDR_ERROR_READ;
 399             else if (rw == 1)
 400                 return MMU_DADDR_ERROR_WRITE;
 401             else
 402                 return MMU_IADDR_ERROR;
 403         }
 404         if (address >= 0x80000000 && address < 0xc0000000) {
 405             /* Mask upper 3 bits for P1 and P2 areas */
 406             *physical = address & 0x1fffffff;
 407         } else {
 408             *physical = address;
 409         }
 410         *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
 411         return MMU_OK;
 412     }
 413
 414     /* If MMU is disabled, return the corresponding physical page */
 415     if (!env->mmucr & MMUCR_AT) {
 416         *physical = address & 0x1FFFFFFF;
 417         *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
 418         return MMU_OK;
 419     }
 420
 421     /* We need to resort to the MMU */
 422     return get_mmu_address(env, physical, prot, address, rw, access_type);
 423 }
 424
 425 int cpu_sh4_handle_mmu_fault(CPUState * env, target_ulong address, int rw,
 426                              int mmu_idx, int is_softmmu)
 427 {
 428     target_ulong physical;
 429     int prot, ret, access_type;
 430
 431     access_type = ACCESS_INT;
 432     ret =
 433         get_physical_address(env, &physical, &prot, address, rw,
 434                              access_type);
 435
 436     if (ret != MMU_OK) {
 437         env->tea = address;
 438         switch (ret) {
 439         case MMU_ITLB_MISS:
 440         case MMU_DTLB_MISS_READ:
 441             env->exception_index = 0x040;
 442             break;
 443         case MMU_DTLB_MULTIPLE:
 444         case MMU_ITLB_MULTIPLE:
 445             env->exception_index = 0x140;
 446             break;
 447         case MMU_ITLB_VIOLATION:
 448             env->exception_index = 0x0a0;
 449             break;
 450         case MMU_DTLB_MISS_WRITE:
 451             env->exception_index = 0x060;
 452             break;
 453         case MMU_DTLB_INITIAL_WRITE:
 454             env->exception_index = 0x080;
 455             break;
 456         case MMU_DTLB_VIOLATION_READ:
 457             env->exception_index = 0x0a0;
 458             break;
 459         case MMU_DTLB_VIOLATION_WRITE:
 460             env->exception_index = 0x0c0;
 461             break;
 462         case MMU_IADDR_ERROR:
 463         case MMU_DADDR_ERROR_READ:
 464             env->exception_index = 0x0c0;
 465             break;
 466         case MMU_DADDR_ERROR_WRITE:
 467             env->exception_index = 0x100;
 468             break;
 469         default:
 470             assert(0);
 471         }
 472         return 1;
 473     }
 474
 475     address &= TARGET_PAGE_MASK;
 476     physical &= TARGET_PAGE_MASK;
 477
 478     return tlb_set_page(env, address, physical, prot, mmu_idx, is_softmmu);
 479 }
 480
 481 target_phys_addr_t cpu_get_phys_page_debug(CPUState * env, target_ulong addr)
 482 {
 483     target_ulong physical;
 484     int prot;
 485
 486     get_physical_address(env, &physical, &prot, addr, 0, 0);
 487     return physical;
 488 }
 489
 490 void cpu_load_tlb(CPUSH4State * env)
 491 {
 492     int n = cpu_mmucr_urc(env->mmucr);
 493     tlb_t * entry = &env->utlb[n];
 494
 495     if (entry->v) {
 496         /* Overwriting valid entry in utlb. */
 497         target_ulong address = entry->vpn << 10;
 498         tlb_flush_page(env, address);
 499     }
 500
 501     /* Take values into cpu status from registers. */
 502     entry->asid = (uint8_t)cpu_pteh_asid(env->pteh);
 503     entry->vpn  = cpu_pteh_vpn(env->pteh);
 504     entry->v    = (uint8_t)cpu_ptel_v(env->ptel);
 505     entry->ppn  = cpu_ptel_ppn(env->ptel);
 506     entry->sz   = (uint8_t)cpu_ptel_sz(env->ptel);
 507     switch (entry->sz) {
 508     case 0: /* 00 */
 509         entry->size = 1024; /* 1K */
 510         break;
 511     case 1: /* 01 */
 512         entry->size = 1024 * 4; /* 4K */
 513         break;
 514     case 2: /* 10 */
 515         entry->size = 1024 * 64; /* 64K */
 516         break;
 517     case 3: /* 11 */
 518         entry->size = 1024 * 1024; /* 1M */
 519         break;
 520     default:
 521         assert(0);
 522         break;
 523     }
 524     entry->sh   = (uint8_t)cpu_ptel_sh(env->ptel);
 525     entry->c    = (uint8_t)cpu_ptel_c(env->ptel);
 526     entry->pr   = (uint8_t)cpu_ptel_pr(env->ptel);
 527     entry->d    = (uint8_t)cpu_ptel_d(env->ptel);
 528     entry->wt   = (uint8_t)cpu_ptel_wt(env->ptel);
 529     entry->sa   = (uint8_t)cpu_ptea_sa(env->ptea);
 530     entry->tc   = (uint8_t)cpu_ptea_tc(env->ptea);
 531 }
 532
 533  void cpu_sh4_invalidate_tlb(CPUSH4State *s)
 534 {
 535     int i;
 536
 537     /* UTLB */
 538     for (i = 0; i < UTLB_SIZE; i++) {
 539         tlb_t * entry = &s->utlb[i];
 540         entry->v = 0;
 541     }
 542     /* ITLB */
 543     for (i = 0; i < UTLB_SIZE; i++) {
 544         tlb_t * entry = &s->utlb[i];
 545         entry->v = 0;
 546     }
 547
 548     tlb_flush(s, 1);
 549 }
 550
 551 void cpu_sh4_write_mmaped_utlb_addr(CPUSH4State *s, target_phys_addr_t addr,
 552                                     uint32_t mem_value)
 553 {
 554     int associate = addr & 0x0000080;
 555     uint32_t vpn = (mem_value & 0xfffffc00) >> 10;
 556     uint8_t d = (uint8_t)((mem_value & 0x00000200) >> 9);
 557     uint8_t v = (uint8_t)((mem_value & 0x00000100) >> 8);
 558     uint8_t asid = (uint8_t)(mem_value & 0x000000ff);
 559     int use_asid = (s->mmucr & MMUCR_SV) == 0 || (s->sr & SR_MD) == 0;
 560
 561     if (associate) {
 562         int i;
 563         tlb_t * utlb_match_entry = NULL;
 564         int needs_tlb_flush = 0;
 565
 566         /* search UTLB */
 567         for (i = 0; i < UTLB_SIZE; i++) {
 568             tlb_t * entry = &s->utlb[i];
 569             if (!entry->v)
 570                 continue;
 571
 572             if (entry->vpn == vpn
 573                 && (!use_asid || entry->asid == asid || entry->sh)) {
 574                 if (utlb_match_entry) {
 575                     /* Multiple TLB Exception */
 576                     s->exception_index = 0x140;
 577                     s->tea = addr;
 578                     break;
 579                 }
 580                 if (entry->v && !v)
 581                     needs_tlb_flush = 1;
 582                 entry->v = v;
 583                 entry->d = d;
 584                 utlb_match_entry = entry;
 585             }
 586             increment_urc(s); /* per utlb access */
 587         }
 588
 589         /* search ITLB */
 590         for (i = 0; i < ITLB_SIZE; i++) {
 591             tlb_t * entry = &s->itlb[i];
 592             if (entry->vpn == vpn
 593                 && (!use_asid || entry->asid == asid || entry->sh)) {
 594                 if (entry->v && !v)
 595                     needs_tlb_flush = 1;
 596                 if (utlb_match_entry)
 597                     *entry = *utlb_match_entry;
 598                 else
 599                     entry->v = v;
 600                 break;
 601             }
 602         }
 603
 604         if (needs_tlb_flush)
 605             tlb_flush_page(s, vpn << 10);
 606
 607     } else {
 608         int index = (addr & 0x00003f00) >> 8;
 609         tlb_t * entry = &s->utlb[index];
 610         if (entry->v) {
 611             /* Overwriting valid entry in utlb. */
 612             target_ulong address = entry->vpn << 10;
 613             tlb_flush_page(s, address);
 614         }
 615         entry->asid = asid;
 616         entry->vpn = vpn;
 617         entry->d = d;
 618         entry->v = v;
 619         increment_urc(s);
 620     }
 621 }
 622
 623 int cpu_sh4_is_cached(CPUSH4State * env, target_ulong addr)
 624 {
 625     int n;
 626     int use_asid = (env->mmucr & MMUCR_SV) == 0 || (env->sr & SR_MD) == 0;
 627
 628     /* check area */
 629     if (env->sr & SR_MD) {
 630         /* For previledged mode, P2 and P4 area is not cachable. */
 631         if ((0xA0000000 <= addr && addr < 0xC0000000) || 0xE0000000 <= addr)
 632             return 0;
 633     } else {
 634         /* For user mode, only U0 area is cachable. */
 635         if (0x80000000 <= addr)
 636             return 0;
 637     }
 638
 639     /*
 640      * TODO : Evaluate CCR and check if the cache is on or off.
 641      *        Now CCR is not in CPUSH4State, but in SH7750State.
 642      *        When you move the ccr inot CPUSH4State, the code will be
 643      *        as follows.
 644      */
 645 #if 0
 646     /* check if operand cache is enabled or not. */
 647     if (!(env->ccr & 1))
 648         return 0;
 649 #endif
 650
 651     /* if MMU is off, no check for TLB. */
 652     if (env->mmucr & MMUCR_AT)
 653         return 1;
 654
 655     /* check TLB */
 656     n = find_tlb_entry(env, addr, env->itlb, ITLB_SIZE, use_asid);
 657     if (n >= 0)
 658         return env->itlb[n].c;
 659
 660     n = find_tlb_entry(env, addr, env->utlb, UTLB_SIZE, use_asid);
 661     if (n >= 0)
 662         return env->utlb[n].c;
 663
 664     return 0;
 665 }
 666
 667 #endif