symexpr.c

一个用在mips体系结构中的操作系统

/*
 * Copyright (C) 1996-1998 by the Board of Trustees
 *    of Leland Stanford Junior University.
 * 
 * This file is part of the SimOS distribution. 
 * See LICENSE file for terms of the license. 
 *
 */


#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include "cpu_interface.h"

#include "symbols.h"
#include "symfile.h"
#include "symexpr.h"
#include "sim_error.h"


/*  CFL:
 *
 *     top   = exec:src:expr | exec:src:int
 *     expr  = *expr | &expr | (typecast) int | term
 *     term  = term.string | term->string | term[ int ] | term < int > | atom
 *     atom  = (expr) | string
 */

#define MAX_STR_LEN 256
#define BUFFER_SIZE 64

int SymParseExpr(ParseInfo *pip);
int SymParseTerm(ParseInfo *pip);
int SymParseAtom(ParseInfo *pip);
int SymParseField(ParseInfo *pip);
int SymDeref(ParseInfo *pip);
int SymParseTypeCast(ParseInfo *pip);
char *SymParseString(ParseInfo *pip);
int SymParseInt(char **str, Reg *val);


static char ename[MAX_STR_LEN];
static char fname[MAX_STR_LEN];

int SymParse(char *symexpr, ParseInfo *pip)
{
   int offset;
   char *str = symexpr;
   int line;
   
   if (sscanf(str, "%[^:]%n", ename, &offset) != 1) {
      ename[0] = '\0';
   } else {
      str += offset;
   }

   if (*str++ != ':') {
      SymReportError("syntax error parsing execname", NULL);
      return SYM_ERROR;
   }

   if (sscanf(str, "%[^:]%n", fname, &offset) != 1) {
      fname[0] = '\0';
   } else {
      str += offset;
   }

   if (*str++ != ':') {
      SymReportError("syntax error parsing source file name", NULL);
      return SYM_ERROR;
   }

   if (isdigit(*str)) {
      /* must be a line number */
      if (sscanf(str, "%i%n", &line, &offset) != 1) {
         SymReportError("expected a line number, got \"", str, "\"", NULL);
         return SYM_ERROR;
      }

      if ((str[0] == '0') && (str[1] == '\0')) {
         ASSERT(line == 0);
         ASSERT(offset == 2);
         /* WAR bug in scanf */
         offset = 1;
      }

      str += offset;
      
      if (SymLine2Addr(ename, fname, line, &(pip->sym)) != SYM_OK) {
         return SYM_ERROR;
      }

      pip->value = SymValue(&(pip->sym));
      pip->constant = 1;
      
   } else {
      pip->execname = ename;
      pip->srcfile = fname;
      pip->str = str;
      pip->internal = (!strcmp(ename, "SIMOS"));
#ifdef __alpha
      if (pip->internal) { 
         return SYM_ERROR;
      }
#endif

      if (SymParseExpr(pip) != SYM_OK) {
         return SYM_ERROR;
      }

      str = pip->str;
   }

   if (*str != '\0') {
      SymReportError("extra characters at end of expression\"", str, "\"", NULL);
      return SYM_ERROR;
   }
   
   return SYM_OK;
}

int SymParseExpr(ParseInfo *pip)
{
   int code;
   
   if (pip->str[0] == '*') {
      pip->str++;

      if ((code = SymParseExpr(pip)) != SYM_OK) {
         return code;
      }

      if ((code = SymDeref(pip)) != SYM_OK) {
         return code;
      }

   } else if (pip->str[0] == '&') {
      pip->str++;

      if ((code = SymParseExpr(pip)) != SYM_OK) {
         return code;
      }

      if (pip->constant) {
         SymReportError("cannot take address of address", NULL);
         return SYM_ERROR;
      }

      SymMakeAddr(&pip->sym);
      pip->constant = 1;

   } else if (pip->str[0] == '(') {
      /*
       *  OK here is the problem. This could be either a type cast or a 
       *  sub-expression. The way to figure this out is to read to the
       *  matching end paren and see if the next token is anything but a
       *  ".", "->", or a "[". We will just let SymParseTypeCast figure
       *  it all out.
       */

      return SymParseTypeCast(pip);
      
   } else {
      return SymParseTerm(pip);
   }

   return SYM_OK;
}

int SymParseTerm(ParseInfo *pip)
{
   int code;

   if ((code = SymParseAtom(pip)) != SYM_OK) {
      return code;
   }
   
   while (1) {
      if (pip->str[0] == '.') {
         pip->str++;
         
         if ((code = SymParseField(pip)) != SYM_OK) {
            return code;
         }
         
      } else if ((pip->str[0] == '-') && (pip->str[1] == '>')) {
         pip->str += 2;

         if ((code = SymDeref(pip)) != SYM_OK) {
            return code;
         }

         if ((code = SymParseField(pip)) != SYM_OK) {
            return code;
         }
         
      } else if ((pip->str[0] == '[') || (pip->str[0] == '<')) {
         Reg val;
         
         pip->str++;

         if ((code = SymDeref(pip)) != SYM_OK) {
            return code;
         }

         if ((code = SymParseInt(&(pip->str), &val)) != SYM_OK) {
            return code;
         }

         if ((pip->str[0] != ']') && (pip->str[0] != '>')) {
            SymReportError("\"]\" or \">\" expected", NULL);
            return SYM_ERROR;
         }

         pip->str++;
         pip->value += val * SymSize(&(pip->sym));

      } else if (pip->str[0] == ':') {
         char *symb;
         
         pip->str++;

         if (SymType(&(pip->sym), SYM_RESOLVE) != tProc) {
            SymReportError("can't use \":\" operator on non-procedure", NULL);
            return SYM_ERROR;
         }

         if (!(symb = SymParseString(pip))) {
            return SYM_ERROR;
         }

         if (!strcmp(symb, "START")) {
            
         } else if (!strcmp(symb, "STARTOPT")) {
            pip->value += 12;

         } else if (!strcmp(symb, "END")) {
            pip->value += SymSize(&(pip->sym)) - 4;

         } else if (SymFind(&(pip->sym), symb, 0) == SYM_OK) {
            if (SymType(&(pip->sym), SYM_RESOLVE) != tLabel) {
               SymReportError("symbol is not a label", NULL);
               return SYM_ERROR;
            }

            pip->value = SymValue(&(pip->sym));

         } else {
            SymReportError("No such label in procedure", NULL);
            return SYM_ERROR;
         }

         return SYM_OK;
         
      } else {
         return SYM_OK;
      }
   }
   return SYM_OK;
}

int SymParseAtom(ParseInfo *pip)
{
   int code;
   int st;
   
   if (pip->str[0] == '(') {
      pip->str++;

      if ((code = SymParseExpr(pip)) != SYM_OK) {
         return code;
      }

      if (pip->str[0] != ')') {
         SymReportError("\")\" expected", NULL);
         return SYM_ERROR;
      }

      pip->str++;

   } else if (isalpha(pip->str[0]) || (pip->str[0] == '_')) {
      char *symb;

      if (!(symb = SymParseString(pip))) {
         return SYM_ERROR;
      }

      
#ifdef DWARF2
      if (Dwarf_SymLookup(pip->execname, pip->srcfile, symb, 0, &(pip->sym)) != SYM_OK) {
         return SYM_ERROR;
      }
#else
      if (SymLookup(pip->execname, pip->srcfile, symb, 0, &(pip->sym)) != SYM_OK) {
         return SYM_ERROR;
      }
#endif
      st = SymType(&(pip->sym), SYM_RESOLVE);
      
      if ((st == tProc) || (st == tArray) || (st == tLabel)) {
         pip->constant = 1;
      } else {
         pip->constant = 0;
      }
      
      pip->value = SymValue(&(pip->sym));

   } else {
      SymReportError("syntax error, expected \".\" or \"->\"", NULL);
      return SYM_ERROR;
   }

   return SYM_OK;
}

int SymParseField(ParseInfo *pip)
{
   char *symb;
   int st;

   st = SymType(&(pip->sym), SYM_RESOLVE);
   
   if ((st != tStruct) && (st != tUnion)) {
      SymReportError("expected a structure", NULL);
      return SYM_ERROR;
   }

   ASSERT(!pip->constant);
   
   if (SymSubtype(&(pip->sym), SYM_RESOLVE) != SYM_OK) {
      return SYM_ERROR;
   }

   st = SymType(&(pip->sym), SYM_RESOLVE);
   
   if ((st != tStructDef) && (st != tUnionDef)) {
      ASSERT(0);
      return SYM_ERROR;
   }

   if (!(symb = SymParseString(pip))) {
      return SYM_ERROR;
   }

   if (SymFind(&(pip->sym), symb, 0) != SYM_OK) {
      return SYM_ERROR;
   }

   st = SymType(&(pip->sym), SYM_RESOLVE);
   
   if (st == tArray) {
      pip->constant = 1;
   } else {
      ASSERT(st != tProc);
   } 


   /* it seems all fields are in bit width */
   ASSERT(!(SymValue(&(pip->sym)) % 8));   
   pip->value += SymValue(&(pip->sym)) / 8;

   return SYM_OK;
}

int SymDeref(ParseInfo *pip)
{
   Reg_s value = 0;
   int st;

   st = SymType(&(pip->sym), SYM_RESOLVE);
   
   if (st == tPtr) {
      if (pip->constant) {
         pip->constant = 0;

      } else if (pip->internal) {
         /*
          * XXX chances are that this is broken
          * XXX for some configurations
          */
#ifdef __alpha
         ASSERT (0);
#else
         pip->value = *(Reg_s*)pip->value;
#endif
         
      } else {
         if (CPUVec.GetMemory(CPUVec.CurrentCpuNum(), pip->value,
                              sizeof(value), (char *)&value) != SUCCESS) {
            SymReportError("addr not mapped", NULL);
            return SYM_ERROR;
         }

         pip->value = BE2HO_4(value);
      }
      
   } else if ((st == tAddr) || (st == tArray)) {
      ASSERT(pip->constant);
      pip->constant = 0;
      
   } else {
      SymReportError("array or pointer expected", NULL);
      return SYM_ERROR;
   }

   ASSERT(!pip->constant);
   
   if (SymSubtype(&(pip->sym), SYM_RESOLVE) != SYM_OK) {
      return SYM_ERROR;
   }

   st = SymType(&(pip->sym), SYM_RESOLVE);

   if (st == tArray) {
      pip->constant = 1;
   } else {
      ASSERT(st != tProc);
   } 
   
   return SYM_OK;
}


/*
 *   Type cast
 */

static char *btNames[] = {
   "char",
   "uchar",
   "short",
   "ushort", 
   "int",
   "uint",
   "long",
   "ulong", 
   "float",
   "double", 
   "struct",
   "union",
   "enum"
};

static int btTypes[] = {
   tChar,
   tUChar,
   tShort,
   tUShort,
   tInt,
   tUInt,
   tLong,
   tULong,
   tFloat,
   tDouble,
   tStruct,
   tUnion,
   tEnum
};

#define NUM_BTS      (sizeof(btNames)/sizeof(char*))

int SymParseTypeCast(ParseInfo *pip)
{
   char *str;
   char *name = "";
   char *scan;
   int level, i;
   int types[6];
   int nextt;
   int bt;
   
   ASSERT(pip->str[0] == '(');

   /* check if it is a typecast */
   for (level=1, scan=pip->str+1; level && *scan; scan++) {
      if (*scan == '(') {
         level++;
      } else if (*scan == ')') {
         level--;
      }
   }

   if ((*scan == '.') || (*scan == '[')
       || (*scan == '<') || (*scan == ')') || (*scan == '\0')
       || ((*scan == '-') && (*(scan+1) == '>'))) {
      /* not a typecast - oh well just parse it as a term */
      return SymParseTerm(pip);
      
   }
   
   /* its a type cast */
   pip->str++;
   nextt = 0;
   
   str = SymParseString(pip);

   bt = -1; 
   for (i=0; i<NUM_BTS; i++) {
      if (!strcmp(str, btNames[i])) {
         bt = btTypes[i];
         break;
      }
   }

   if (i == NUM_BTS) {
      name = str;
      bt = tTypedef;

   } else if ((bt == tStruct)
       || (bt == tUnion)
       || (bt == tEnum)) {
      while (*pip->str == ' ') {
         pip->str++;
      }
      name = SymParseString(pip);
      
   } else {
      name = "";
   }

   while (1) {
      while (*pip->str == ' ') {
         pip->str++;
      }
      
      if (pip->str[0] == '*') {
         types[nextt++] = tPtr;
         pip->str++;
      } else {
         break;
      }
   }

   types[nextt++] = bt;
   types[nextt++] = tNil;

   if ((types[0] != tPtr) && !((types[0] >= tChar) && (types[0] <= tDouble))) {
      SymReportError("Can only cast to pointer or basic type", NULL);
      return SYM_ERROR;      
   }
   
   if (pip->str[0] != ')') {
      SymReportError("Syntax error in type cast", NULL);
      return SYM_ERROR;
   }

   pip->str++;
   
   if (SymParseInt(&(pip->str), &(pip->value)) == SYM_OK) {
      pip->constant = 1;
   } else {
      SymReportError("Only type casting hard coded constants suported so far. Sorry.",
                     NULL);
      return SYM_ERROR;
#ifdef notdef
      /* XXX fix */
      if ((code = SymParseExpr(pip)) != SYM_OK) {
         return code;
      }
      pip->constant = 0;
#endif
   }

#ifdef DWARF2_not
   if (Dwarf_SymTypeCast(pip->execname, pip->srcfile, types, name, &(pip->sym)) != SYM_OK) {
      return SYM_ERROR;
   }
#else
   if (SymTypeCast(pip->execname, pip->srcfile, types, name, &(pip->sym)) != SYM_OK) {
      return SYM_ERROR;
   }
#endif

   return SYM_OK;
}

int SymParseInt(char **str, Reg *val)
{
   int offset;

   while (**str == ' ') {
      (*str)++;
   }

   if (isdigit(**str)) {
      int i;
      uint64 val64=0;
#ifdef __alpha
      i = sscanf(*str, "%li%n", &val64, &offset);
#else
      i = sscanf(*str, "%lli%n", &val64, &offset);
#endif
      *val = val64;

      if (i != 1) {
         return SYM_ERROR;
      }
      *str += offset;

      while (**str == ' ') {
         (*str)++;
      }
      
   } else {
      SymReportError("expected an int, got \"", str, "\"", NULL);
      return SYM_ERROR;
   }

   return SYM_OK;
}

char *SymParseString(ParseInfo *pip)
{
   static char buf[BUFFER_SIZE];
   char *dst = buf;

   while (isalnum(*(pip->str)) || (*(pip->str) == '_')) {
      if ((dst - buf) == (BUFFER_SIZE-1)) {
         SymReportError("symbol overflowed internal buffers (internal error)", NULL);
         return NULL;
      }
      *dst++ = *(pip->str)++;
   }

   *dst = '\0';

   if (!buf[0]) {
      SymReportError("expected a string", NULL);
   }
   
   return buf;
}