dynasm/dasm_mips.h

   1 /*
   2 ** DynASM MIPS encoding engine.
   3 ** Copyright (C) 2005-2023 Mike Pall. All rights reserved.
   4 ** Released under the MIT license. See dynasm.lua for full copyright notice.
   5 */
   6
   7 #include <stddef.h>
   8 #include <stdarg.h>
   9 #include <string.h>
  10 #include <stdlib.h>
  11
  12 #define DASM_ARCH               "mips"
  13
  14 #ifndef DASM_EXTERN
  15 #define DASM_EXTERN(a,b,c,d)    0
  16 #endif
  17
  18 /* Action definitions. */
  19 enum {
  20   DASM_STOP, DASM_SECTION, DASM_ESC, DASM_REL_EXT,
  21   /* The following actions need a buffer position. */
  22   DASM_ALIGN, DASM_REL_LG, DASM_LABEL_LG,
  23   /* The following actions also have an argument. */
  24   DASM_REL_PC, DASM_LABEL_PC, DASM_IMM, DASM_IMMS,
  25   DASM__MAX
  26 };
  27
  28 /* Maximum number of section buffer positions for a single dasm_put() call. */
  29 #define DASM_MAXSECPOS          25
  30
  31 /* DynASM encoder status codes. Action list offset or number are or'ed in. */
  32 #define DASM_S_OK               0x00000000
  33 #define DASM_S_NOMEM            0x01000000
  34 #define DASM_S_PHASE            0x02000000
  35 #define DASM_S_MATCH_SEC        0x03000000
  36 #define DASM_S_RANGE_I          0x11000000
  37 #define DASM_S_RANGE_SEC        0x12000000
  38 #define DASM_S_RANGE_LG         0x13000000
  39 #define DASM_S_RANGE_PC         0x14000000
  40 #define DASM_S_RANGE_REL        0x15000000
  41 #define DASM_S_UNDEF_LG         0x21000000
  42 #define DASM_S_UNDEF_PC         0x22000000
  43
  44 /* Macros to convert positions (8 bit section + 24 bit index). */
  45 #define DASM_POS2IDX(pos)       ((pos)&0x00ffffff)
  46 #define DASM_POS2BIAS(pos)      ((pos)&0xff000000)
  47 #define DASM_SEC2POS(sec)       ((sec)<<24)
  48 #define DASM_POS2SEC(pos)       ((pos)>>24)
  49 #define DASM_POS2PTR(D, pos)    (D->sections[DASM_POS2SEC(pos)].rbuf + (pos))
  50
  51 /* Action list type. */
  52 typedef const unsigned int *dasm_ActList;
  53
  54 /* Per-section structure. */
  55 typedef struct dasm_Section {
  56   int *rbuf;            /* Biased buffer pointer (negative section bias). */
  57   int *buf;             /* True buffer pointer. */
  58   size_t bsize;         /* Buffer size in bytes. */
  59   int pos;              /* Biased buffer position. */
  60   int epos;             /* End of biased buffer position - max single put. */
  61   int ofs;              /* Byte offset into section. */
  62 } dasm_Section;
  63
  64 /* Core structure holding the DynASM encoding state. */
  65 struct dasm_State {
  66   size_t psize;                 /* Allocated size of this structure. */
  67   dasm_ActList actionlist;      /* Current actionlist pointer. */
  68   int *lglabels;                /* Local/global chain/pos ptrs. */
  69   size_t lgsize;
  70   int *pclabels;                /* PC label chains/pos ptrs. */
  71   size_t pcsize;
  72   void **globals;               /* Array of globals. */
  73   dasm_Section *section;        /* Pointer to active section. */
  74   size_t codesize;              /* Total size of all code sections. */
  75   int maxsection;               /* 0 <= sectionidx < maxsection. */
  76   int status;                   /* Status code. */
  77   dasm_Section sections[1];     /* All sections. Alloc-extended. */
  78 };
  79
  80 /* The size of the core structure depends on the max. number of sections. */
  81 #define DASM_PSZ(ms)    (sizeof(dasm_State)+(ms-1)*sizeof(dasm_Section))
  82
  83
  84 /* Initialize DynASM state. */
  85 void dasm_init(Dst_DECL, int maxsection)
  86 {
  87   dasm_State *D;
  88   size_t psz = 0;
  89   Dst_REF = NULL;
  90   DASM_M_GROW(Dst, struct dasm_State, Dst_REF, psz, DASM_PSZ(maxsection));
  91   D = Dst_REF;
  92   D->psize = psz;
  93   D->lglabels = NULL;
  94   D->lgsize = 0;
  95   D->pclabels = NULL;
  96   D->pcsize = 0;
  97   D->globals = NULL;
  98   D->maxsection = maxsection;
  99   memset((void *)D->sections, 0, maxsection * sizeof(dasm_Section));
 100 }
 101
 102 /* Free DynASM state. */
 103 void dasm_free(Dst_DECL)
 104 {
 105   dasm_State *D = Dst_REF;
 106   int i;
 107   for (i = 0; i < D->maxsection; i++)
 108     if (D->sections[i].buf)
 109       DASM_M_FREE(Dst, D->sections[i].buf, D->sections[i].bsize);
 110   if (D->pclabels) DASM_M_FREE(Dst, D->pclabels, D->pcsize);
 111   if (D->lglabels) DASM_M_FREE(Dst, D->lglabels, D->lgsize);
 112   DASM_M_FREE(Dst, D, D->psize);
 113 }
 114
 115 /* Setup global label array. Must be called before dasm_setup(). */
 116 void dasm_setupglobal(Dst_DECL, void **gl, unsigned int maxgl)
 117 {
 118   dasm_State *D = Dst_REF;
 119   D->globals = gl;
 120   DASM_M_GROW(Dst, int, D->lglabels, D->lgsize, (10+maxgl)*sizeof(int));
 121 }
 122
 123 /* Grow PC label array. Can be called after dasm_setup(), too. */
 124 void dasm_growpc(Dst_DECL, unsigned int maxpc)
 125 {
 126   dasm_State *D = Dst_REF;
 127   size_t osz = D->pcsize;
 128   DASM_M_GROW(Dst, int, D->pclabels, D->pcsize, maxpc*sizeof(int));
 129   memset((void *)(((unsigned char *)D->pclabels)+osz), 0, D->pcsize-osz);
 130 }
 131
 132 /* Setup encoder. */
 133 void dasm_setup(Dst_DECL, const void *actionlist)
 134 {
 135   dasm_State *D = Dst_REF;
 136   int i;
 137   D->actionlist = (dasm_ActList)actionlist;
 138   D->status = DASM_S_OK;
 139   D->section = &D->sections[0];
 140   memset((void *)D->lglabels, 0, D->lgsize);
 141   if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize);
 142   for (i = 0; i < D->maxsection; i++) {
 143     D->sections[i].pos = DASM_SEC2POS(i);
 144     D->sections[i].rbuf = D->sections[i].buf - D->sections[i].pos;
 145     D->sections[i].ofs = 0;
 146   }
 147 }
 148
 149
 150 #ifdef DASM_CHECKS
 151 #define CK(x, st) \
 152   do { if (!(x)) { \
 153     D->status = DASM_S_##st|(int)(p-D->actionlist-1); return; } } while (0)
 154 #define CKPL(kind, st) \
 155   do { if ((size_t)((char *)pl-(char *)D->kind##labels) >= D->kind##size) { \
 156     D->status = DASM_S_RANGE_##st|(int)(p-D->actionlist-1); return; } } while (0)
 157 #else
 158 #define CK(x, st)       ((void)0)
 159 #define CKPL(kind, st)  ((void)0)
 160 #endif
 161
 162 /* Pass 1: Store actions and args, link branches/labels, estimate offsets. */
 163 void dasm_put(Dst_DECL, int start, ...)
 164 {
 165   va_list ap;
 166   dasm_State *D = Dst_REF;
 167   dasm_ActList p = D->actionlist + start;
 168   dasm_Section *sec = D->section;
 169   int pos = sec->pos, ofs = sec->ofs;
 170   int *b;
 171
 172   if (pos >= sec->epos) {
 173     DASM_M_GROW(Dst, int, sec->buf, sec->bsize,
 174       sec->bsize + 2*DASM_MAXSECPOS*sizeof(int));
 175     sec->rbuf = sec->buf - DASM_POS2BIAS(pos);
 176     sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos);
 177   }
 178
 179   b = sec->rbuf;
 180   b[pos++] = start;
 181
 182   va_start(ap, start);
 183   while (1) {
 184     unsigned int ins = *p++;
 185     unsigned int action = (ins >> 16) - 0xff00;
 186     if (action >= DASM__MAX) {
 187       ofs += 4;
 188     } else {
 189       int *pl, n = action >= DASM_REL_PC ? va_arg(ap, int) : 0;
 190       switch (action) {
 191       case DASM_STOP: goto stop;
 192       case DASM_SECTION:
 193         n = (ins & 255); CK(n < D->maxsection, RANGE_SEC);
 194         D->section = &D->sections[n]; goto stop;
 195       case DASM_ESC: p++; ofs += 4; break;
 196       case DASM_REL_EXT: break;
 197       case DASM_ALIGN: ofs += (ins & 255); b[pos++] = ofs; break;
 198       case DASM_REL_LG:
 199         n = (ins & 2047) - 10; pl = D->lglabels + n;
 200         /* Bkwd rel or global. */
 201         if (n >= 0) { CK(n>=10||*pl<0, RANGE_LG); CKPL(lg, LG); goto putrel; }
 202         pl += 10; n = *pl;
 203         if (n < 0) n = 0;  /* Start new chain for fwd rel if label exists. */
 204         goto linkrel;
 205       case DASM_REL_PC:
 206         pl = D->pclabels + n; CKPL(pc, PC);
 207       putrel:
 208         n = *pl;
 209         if (n < 0) {  /* Label exists. Get label pos and store it. */
 210           b[pos] = -n;
 211         } else {
 212       linkrel:
 213           b[pos] = n;  /* Else link to rel chain, anchored at label. */
 214           *pl = pos;
 215         }
 216         pos++;
 217         break;
 218       case DASM_LABEL_LG:
 219         pl = D->lglabels + (ins & 2047) - 10; CKPL(lg, LG); goto putlabel;
 220       case DASM_LABEL_PC:
 221         pl = D->pclabels + n; CKPL(pc, PC);
 222       putlabel:
 223         n = *pl;  /* n > 0: Collapse rel chain and replace with label pos. */
 224         while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos;
 225         }
 226         *pl = -pos;  /* Label exists now. */
 227         b[pos++] = ofs;  /* Store pass1 offset estimate. */
 228         break;
 229       case DASM_IMM: case DASM_IMMS:
 230 #ifdef DASM_CHECKS
 231         CK((n & ((1<<((ins>>10)&31))-1)) == 0, RANGE_I);
 232 #endif
 233         n >>= ((ins>>10)&31);
 234 #ifdef DASM_CHECKS
 235         if (ins & 0x8000)
 236           CK(((n + (1<<(((ins>>5)&31)-1)))>>((ins>>5)&31)) == 0, RANGE_I);
 237         else
 238           CK((n>>((ins>>5)&31)) == 0, RANGE_I);
 239 #endif
 240         b[pos++] = n;
 241         break;
 242       }
 243     }
 244   }
 245 stop:
 246   va_end(ap);
 247   sec->pos = pos;
 248   sec->ofs = ofs;
 249 }
 250 #undef CK
 251
 252 /* Pass 2: Link sections, shrink aligns, fix label offsets. */
 253 int dasm_link(Dst_DECL, size_t *szp)
 254 {
 255   dasm_State *D = Dst_REF;
 256   int secnum;
 257   int ofs = 0;
 258
 259 #ifdef DASM_CHECKS
 260   *szp = 0;
 261   if (D->status != DASM_S_OK) return D->status;
 262   {
 263     int pc;
 264     for (pc = 0; pc*sizeof(int) < D->pcsize; pc++)
 265       if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc;
 266   }
 267 #endif
 268
 269   { /* Handle globals not defined in this translation unit. */
 270     int idx;
 271     for (idx = 10; idx*sizeof(int) < D->lgsize; idx++) {
 272       int n = D->lglabels[idx];
 273       /* Undefined label: Collapse rel chain and replace with marker (< 0). */
 274       while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; }
 275     }
 276   }
 277
 278   /* Combine all code sections. No support for data sections (yet). */
 279   for (secnum = 0; secnum < D->maxsection; secnum++) {
 280     dasm_Section *sec = D->sections + secnum;
 281     int *b = sec->rbuf;
 282     int pos = DASM_SEC2POS(secnum);
 283     int lastpos = sec->pos;
 284
 285     while (pos != lastpos) {
 286       dasm_ActList p = D->actionlist + b[pos++];
 287       while (1) {
 288         unsigned int ins = *p++;
 289         unsigned int action = (ins >> 16) - 0xff00;
 290         switch (action) {
 291         case DASM_STOP: case DASM_SECTION: goto stop;
 292         case DASM_ESC: p++; break;
 293         case DASM_REL_EXT: break;
 294         case DASM_ALIGN: ofs -= (b[pos++] + ofs) & (ins & 255); break;
 295         case DASM_REL_LG: case DASM_REL_PC: pos++; break;
 296         case DASM_LABEL_LG: case DASM_LABEL_PC: b[pos++] += ofs; break;
 297         case DASM_IMM: case DASM_IMMS: pos++; break;
 298         }
 299       }
 300       stop: (void)0;
 301     }
 302     ofs += sec->ofs;  /* Next section starts right after current section. */
 303   }
 304
 305   D->codesize = ofs;  /* Total size of all code sections */
 306   *szp = ofs;
 307   return DASM_S_OK;
 308 }
 309
 310 #ifdef DASM_CHECKS
 311 #define CK(x, st) \
 312   do { if (!(x)) return DASM_S_##st|(int)(p-D->actionlist-1); } while (0)
 313 #else
 314 #define CK(x, st)       ((void)0)
 315 #endif
 316
 317 /* Pass 3: Encode sections. */
 318 int dasm_encode(Dst_DECL, void *buffer)
 319 {
 320   dasm_State *D = Dst_REF;
 321   char *base = (char *)buffer;
 322   unsigned int *cp = (unsigned int *)buffer;
 323   int secnum;
 324
 325   /* Encode all code sections. No support for data sections (yet). */
 326   for (secnum = 0; secnum < D->maxsection; secnum++) {
 327     dasm_Section *sec = D->sections + secnum;
 328     int *b = sec->buf;
 329     int *endb = sec->rbuf + sec->pos;
 330
 331     while (b != endb) {
 332       dasm_ActList p = D->actionlist + *b++;
 333       while (1) {
 334         unsigned int ins = *p++;
 335         unsigned int action = (ins >> 16) - 0xff00;
 336         int n = (action >= DASM_ALIGN && action < DASM__MAX) ? *b++ : 0;
 337         switch (action) {
 338         case DASM_STOP: case DASM_SECTION: goto stop;
 339         case DASM_ESC: *cp++ = *p++; break;
 340         case DASM_REL_EXT:
 341           n = DASM_EXTERN(Dst, (unsigned char *)cp, (ins & 2047), 1);
 342           goto patchrel;
 343         case DASM_ALIGN:
 344           ins &= 255; while ((((char *)cp - base) & ins)) *cp++ = 0x60000000;
 345           break;
 346         case DASM_REL_LG:
 347           if (n < 0) {
 348             n = (int)((ptrdiff_t)D->globals[-n-10] - (ptrdiff_t)cp);
 349             goto patchrel;
 350           }
 351           /* fallthrough */
 352         case DASM_REL_PC:
 353           CK(n >= 0, UNDEF_PC);
 354           n = *DASM_POS2PTR(D, n);
 355           if (ins & 2048)
 356             n = (n + (int)(size_t)base) & 0x0fffffff;
 357           else
 358             n = n - (int)((char *)cp - base);
 359         patchrel: {
 360           unsigned int e = 16 + ((ins >> 12) & 15);
 361           CK((n & 3) == 0 &&
 362              ((n + ((ins & 2048) ? 0 : (1<<(e+1)))) >> (e+2)) == 0, RANGE_REL);
 363           cp[-1] |= ((n>>2) & ((1<<e)-1));
 364           }
 365           break;
 366         case DASM_LABEL_LG:
 367           ins &= 2047; if (ins >= 20) D->globals[ins-20] = (void *)(base + n);
 368           break;
 369         case DASM_LABEL_PC: break;
 370         case DASM_IMMS:
 371           cp[-1] |= ((n>>3) & 4); n &= 0x1f;
 372           /* fallthrough */
 373         case DASM_IMM:
 374           cp[-1] |= (n & ((1<<((ins>>5)&31))-1)) << (ins&31);
 375           break;
 376         default: *cp++ = ins; break;
 377         }
 378       }
 379       stop: (void)0;
 380     }
 381   }
 382
 383   if (base + D->codesize != (char *)cp)  /* Check for phase errors. */
 384     return DASM_S_PHASE;
 385   return DASM_S_OK;
 386 }
 387 #undef CK
 388
 389 /* Get PC label offset. */
 390 int dasm_getpclabel(Dst_DECL, unsigned int pc)
 391 {
 392   dasm_State *D = Dst_REF;
 393   if (pc*sizeof(int) < D->pcsize) {
 394     int pos = D->pclabels[pc];
 395     if (pos < 0) return *DASM_POS2PTR(D, -pos);
 396     if (pos > 0) return -1;  /* Undefined. */
 397   }
 398   return -2;  /* Unused or out of range. */
 399 }
 400
 401 #ifdef DASM_CHECKS
 402 /* Optional sanity checker to call between isolated encoding steps. */
 403 int dasm_checkstep(Dst_DECL, int secmatch)
 404 {
 405   dasm_State *D = Dst_REF;
 406   if (D->status == DASM_S_OK) {
 407     int i;
 408     for (i = 1; i <= 9; i++) {
 409       if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_LG|i; break; }
 410       D->lglabels[i] = 0;
 411     }
 412   }
 413   if (D->status == DASM_S_OK && secmatch >= 0 &&
 414       D->section != &D->sections[secmatch])
 415     D->status = DASM_S_MATCH_SEC|(int)(D->section-D->sections);
 416   return D->status;
 417 }
 418 #endif
 419