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,
  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 (bias -10). */
  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   int i;
  90   Dst_REF = NULL;
  91   DASM_M_GROW(Dst, struct dasm_State, Dst_REF, psz, DASM_PSZ(maxsection));
  92   D = Dst_REF;
  93   D->psize = psz;
  94   D->lglabels = NULL;
  95   D->lgsize = 0;
  96   D->pclabels = NULL;
  97   D->pcsize = 0;
  98   D->globals = NULL;
  99   D->maxsection = maxsection;
 100   for (i = 0; i < maxsection; i++) {
 101     D->sections[i].buf = NULL;  /* Need this for pass3. */
 102     D->sections[i].rbuf = D->sections[i].buf - DASM_SEC2POS(i);
 103     D->sections[i].bsize = 0;
 104     D->sections[i].epos = 0;  /* Wrong, but is recalculated after resize. */
 105   }
 106 }
 107
 108 /* Free DynASM state. */
 109 void dasm_free(Dst_DECL)
 110 {
 111   dasm_State *D = Dst_REF;
 112   int i;
 113   for (i = 0; i < D->maxsection; i++)
 114     if (D->sections[i].buf)
 115       DASM_M_FREE(Dst, D->sections[i].buf, D->sections[i].bsize);
 116   if (D->pclabels) DASM_M_FREE(Dst, D->pclabels, D->pcsize);
 117   if (D->lglabels) DASM_M_FREE(Dst, D->lglabels, D->lgsize);
 118   DASM_M_FREE(Dst, D, D->psize);
 119 }
 120
 121 /* Setup global label array. Must be called before dasm_setup(). */
 122 void dasm_setupglobal(Dst_DECL, void **gl, unsigned int maxgl)
 123 {
 124   dasm_State *D = Dst_REF;
 125   D->globals = gl - 10;  /* Negative bias to compensate for locals. */
 126   DASM_M_GROW(Dst, int, D->lglabels, D->lgsize, (10+maxgl)*sizeof(int));
 127 }
 128
 129 /* Grow PC label array. Can be called after dasm_setup(), too. */
 130 void dasm_growpc(Dst_DECL, unsigned int maxpc)
 131 {
 132   dasm_State *D = Dst_REF;
 133   size_t osz = D->pcsize;
 134   DASM_M_GROW(Dst, int, D->pclabels, D->pcsize, maxpc*sizeof(int));
 135   memset((void *)(((unsigned char *)D->pclabels)+osz), 0, D->pcsize-osz);
 136 }
 137
 138 /* Setup encoder. */
 139 void dasm_setup(Dst_DECL, const void *actionlist)
 140 {
 141   dasm_State *D = Dst_REF;
 142   int i;
 143   D->actionlist = (dasm_ActList)actionlist;
 144   D->status = DASM_S_OK;
 145   D->section = &D->sections[0];
 146   memset((void *)D->lglabels, 0, D->lgsize);
 147   if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize);
 148   for (i = 0; i < D->maxsection; i++) {
 149     D->sections[i].pos = DASM_SEC2POS(i);
 150     D->sections[i].ofs = 0;
 151   }
 152 }
 153
 154
 155 #ifdef DASM_CHECKS
 156 #define CK(x, st) \
 157   do { if (!(x)) { \
 158     D->status = DASM_S_##st|(p-D->actionlist-1); return; } } while (0)
 159 #define CKPL(kind, st) \
 160   do { if ((size_t)((char *)pl-(char *)D->kind##labels) >= D->kind##size) { \
 161     D->status = DASM_S_RANGE_##st|(p-D->actionlist-1); return; } } while (0)
 162 #else
 163 #define CK(x, st)       ((void)0)
 164 #define CKPL(kind, st)  ((void)0)
 165 #endif
 166
 167 /* Pass 1: Store actions and args, link branches/labels, estimate offsets. */
 168 void dasm_put(Dst_DECL, int start, ...)
 169 {
 170   va_list ap;
 171   dasm_State *D = Dst_REF;
 172   dasm_ActList p = D->actionlist + start;
 173   dasm_Section *sec = D->section;
 174   int pos = sec->pos, ofs = sec->ofs;
 175   int *b;
 176
 177   if (pos >= sec->epos) {
 178     DASM_M_GROW(Dst, int, sec->buf, sec->bsize,
 179       sec->bsize + 2*DASM_MAXSECPOS*sizeof(int));
 180     sec->rbuf = sec->buf - DASM_POS2BIAS(pos);
 181     sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos);
 182   }
 183
 184   b = sec->rbuf;
 185   b[pos++] = start;
 186
 187   va_start(ap, start);
 188   while (1) {
 189     unsigned int ins = *p++;
 190     unsigned int action = (ins >> 16) - 0xff00;
 191     if (action >= DASM__MAX) {
 192       ofs += 4;
 193     } else {
 194       int *pl, n = action >= DASM_REL_PC ? va_arg(ap, int) : 0;
 195       switch (action) {
 196       case DASM_STOP: goto stop;
 197       case DASM_SECTION:
 198         n = (ins & 255); CK(n < D->maxsection, RANGE_SEC);
 199         D->section = &D->sections[n]; goto stop;
 200       case DASM_ESC: p++; ofs += 4; break;
 201       case DASM_REL_EXT: break;
 202       case DASM_ALIGN: ofs += (ins & 255); b[pos++] = ofs; break;
 203       case DASM_REL_LG:
 204         n = (ins & 2047) - 10; pl = D->lglabels + n;
 205         /* Bkwd rel or global. */
 206         if (n >= 0) { CK(n>=10||*pl<0, RANGE_LG); CKPL(lg, LG); goto putrel; }
 207         pl += 10; n = *pl;
 208         if (n < 0) n = 0;  /* Start new chain for fwd rel if label exists. */
 209         goto linkrel;
 210       case DASM_REL_PC:
 211         pl = D->pclabels + n; CKPL(pc, PC);
 212       putrel:
 213         n = *pl;
 214         if (n < 0) {  /* Label exists. Get label pos and store it. */
 215           b[pos] = -n;
 216         } else {
 217       linkrel:
 218           b[pos] = n;  /* Else link to rel chain, anchored at label. */
 219           *pl = pos;
 220         }
 221         pos++;
 222         break;
 223       case DASM_LABEL_LG:
 224         pl = D->lglabels + (ins & 2047) - 10; CKPL(lg, LG); goto putlabel;
 225       case DASM_LABEL_PC:
 226         pl = D->pclabels + n; CKPL(pc, PC);
 227       putlabel:
 228         n = *pl;  /* n > 0: Collapse rel chain and replace with label pos. */
 229         while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos;
 230         }
 231         *pl = -pos;  /* Label exists now. */
 232         b[pos++] = ofs;  /* Store pass1 offset estimate. */
 233         break;
 234       case DASM_IMM:
 235 #ifdef DASM_CHECKS
 236         CK((n & ((1<<((ins>>10)&31))-1)) == 0, RANGE_I);
 237 #endif
 238         n >>= ((ins>>10)&31);
 239 #ifdef DASM_CHECKS
 240         if (ins & 0x8000)
 241           CK(((n + (1<<(((ins>>5)&31)-1)))>>((ins>>5)&31)) == 0, RANGE_I);
 242         else
 243           CK((n>>((ins>>5)&31)) == 0, RANGE_I);
 244 #endif
 245         b[pos++] = n;
 246         break;
 247       }
 248     }
 249   }
 250 stop:
 251   va_end(ap);
 252   sec->pos = pos;
 253   sec->ofs = ofs;
 254 }
 255 #undef CK
 256
 257 /* Pass 2: Link sections, shrink aligns, fix label offsets. */
 258 int dasm_link(Dst_DECL, size_t *szp)
 259 {
 260   dasm_State *D = Dst_REF;
 261   int secnum;
 262   int ofs = 0;
 263
 264 #ifdef DASM_CHECKS
 265   *szp = 0;
 266   if (D->status != DASM_S_OK) return D->status;
 267   {
 268     int pc;
 269     for (pc = 0; pc*sizeof(int) < D->pcsize; pc++)
 270       if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc;
 271   }
 272 #endif
 273
 274   { /* Handle globals not defined in this translation unit. */
 275     int idx;
 276     for (idx = 20; idx*sizeof(int) < D->lgsize; idx++) {
 277       int n = D->lglabels[idx];
 278       /* Undefined label: Collapse rel chain and replace with marker (< 0). */
 279       while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; }
 280     }
 281   }
 282
 283   /* Combine all code sections. No support for data sections (yet). */
 284   for (secnum = 0; secnum < D->maxsection; secnum++) {
 285     dasm_Section *sec = D->sections + secnum;
 286     int *b = sec->rbuf;
 287     int pos = DASM_SEC2POS(secnum);
 288     int lastpos = sec->pos;
 289
 290     while (pos != lastpos) {
 291       dasm_ActList p = D->actionlist + b[pos++];
 292       while (1) {
 293         unsigned int ins = *p++;
 294         unsigned int action = (ins >> 16) - 0xff00;
 295         switch (action) {
 296         case DASM_STOP: case DASM_SECTION: goto stop;
 297         case DASM_ESC: p++; break;
 298         case DASM_REL_EXT: break;
 299         case DASM_ALIGN: ofs -= (b[pos++] + ofs) & (ins & 255); break;
 300         case DASM_REL_LG: case DASM_REL_PC: pos++; break;
 301         case DASM_LABEL_LG: case DASM_LABEL_PC: b[pos++] += ofs; break;
 302         case DASM_IMM: pos++; break;
 303         }
 304       }
 305       stop: (void)0;
 306     }
 307     ofs += sec->ofs;  /* Next section starts right after current section. */
 308   }
 309
 310   D->codesize = ofs;  /* Total size of all code sections */
 311   *szp = ofs;
 312   return DASM_S_OK;
 313 }
 314
 315 #ifdef DASM_CHECKS
 316 #define CK(x, st) \
 317   do { if (!(x)) return DASM_S_##st|(p-D->actionlist-1); } while (0)
 318 #else
 319 #define CK(x, st)       ((void)0)
 320 #endif
 321
 322 /* Pass 3: Encode sections. */
 323 int dasm_encode(Dst_DECL, void *buffer)
 324 {
 325   dasm_State *D = Dst_REF;
 326   char *base = (char *)buffer;
 327   unsigned int *cp = (unsigned int *)buffer;
 328   int secnum;
 329
 330   /* Encode all code sections. No support for data sections (yet). */
 331   for (secnum = 0; secnum < D->maxsection; secnum++) {
 332     dasm_Section *sec = D->sections + secnum;
 333     int *b = sec->buf;
 334     int *endb = sec->rbuf + sec->pos;
 335
 336     while (b != endb) {
 337       dasm_ActList p = D->actionlist + *b++;
 338       while (1) {
 339         unsigned int ins = *p++;
 340         unsigned int action = (ins >> 16) - 0xff00;
 341         int n = (action >= DASM_ALIGN && action < DASM__MAX) ? *b++ : 0;
 342         switch (action) {
 343         case DASM_STOP: case DASM_SECTION: goto stop;
 344         case DASM_ESC: *cp++ = *p++; break;
 345         case DASM_REL_EXT:
 346           n = DASM_EXTERN(Dst, (unsigned char *)cp, (ins & 2047), 1);
 347           goto patchrel;
 348         case DASM_ALIGN:
 349           ins &= 255; while ((((char *)cp - base) & ins)) *cp++ = 0x60000000;
 350           break;
 351         case DASM_REL_LG:
 352           CK(n >= 0, UNDEF_LG);
 353           /* fallthrough */
 354         case DASM_REL_PC:
 355           CK(n >= 0, UNDEF_PC);
 356           n = *DASM_POS2PTR(D, n);
 357           if (ins & 2048)
 358             n = n - (int)((char *)cp - base);
 359           else
 360             n = (n + (int)base) & 0x0fffffff;
 361         patchrel:
 362           CK((n & 3) == 0 &&
 363              ((n + ((ins & 2048) ? 0x00020000 : 0)) >>
 364                ((ins & 2048) ? 18 : 28)) == 0, RANGE_REL);
 365           cp[-1] |= ((n>>2) & ((ins & 2048) ? 0x0000ffff: 0x03ffffff));
 366           break;
 367         case DASM_LABEL_LG:
 368           ins &= 2047; if (ins >= 20) D->globals[ins-10] = (void *)(base + n);
 369           break;
 370         case DASM_LABEL_PC: break;
 371         case DASM_IMM:
 372           cp[-1] |= (n & ((1<<((ins>>5)&31))-1)) << (ins&31);
 373           break;
 374         default: *cp++ = ins; break;
 375         }
 376       }
 377       stop: (void)0;
 378     }
 379   }
 380
 381   if (base + D->codesize != (char *)cp)  /* Check for phase errors. */
 382     return DASM_S_PHASE;
 383   return DASM_S_OK;
 384 }
 385 #undef CK
 386
 387 /* Get PC label offset. */
 388 int dasm_getpclabel(Dst_DECL, unsigned int pc)
 389 {
 390   dasm_State *D = Dst_REF;
 391   if (pc*sizeof(int) < D->pcsize) {
 392     int pos = D->pclabels[pc];
 393     if (pos < 0) return *DASM_POS2PTR(D, -pos);
 394     if (pos > 0) return -1;  /* Undefined. */
 395   }
 396   return -2;  /* Unused or out of range. */
 397 }
 398
 399 #ifdef DASM_CHECKS
 400 /* Optional sanity checker to call between isolated encoding steps. */
 401 int dasm_checkstep(Dst_DECL, int secmatch)
 402 {
 403   dasm_State *D = Dst_REF;
 404   if (D->status == DASM_S_OK) {
 405     int i;
 406     for (i = 1; i <= 9; i++) {
 407       if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_LG|i; break; }
 408       D->lglabels[i] = 0;
 409     }
 410   }
 411   if (D->status == DASM_S_OK && secmatch >= 0 &&
 412       D->section != &D->sections[secmatch])
 413     D->status = DASM_S_MATCH_SEC|(D->section-D->sections);
 414   return D->status;
 415 }
 416 #endif
 417