symbol.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <stdlib.h>
   4
   5 #include "error.h"
   6 #include "parse.h"
   7 #include "symbol.h"
   8
   9 struct symbol_hash symbol_hash[HASH_SIZE];
  10
  11 int ram_address = 16;
  12 int rom_address = 0;
  13
  14 void inc_rom_address()
  15 {
  16         ++rom_address;
  17 }
  18
  19 int get_rom_address()
  20 {
  21         return rom_address;
  22 }
  23
  24 int get_ram_address()
  25 {
  26         return ram_address;
  27 }
  28
  29 void print_hash()
  30 {
  31         int i = 0;
  32         printf("---------- HASH TABLE ----------\n");
  33         printf("Position\tAdd\tName\n");
  34         while(i < HASH_SIZE)
  35         {
  36                 if(symbol_hash[i].name[0] != '\0')
  37                 {
  38                         printf("HASH: %d\t%d\t%s\n", i, symbol_hash[i].address, symbol_hash[i].name);
  39                 }
  40                 ++i;
  41         }
  42 }
  43
  44 int hash(char symbol[])
  45 {
  46         int hash = 0;
  47         int i = 0;
  48         while(symbol[i] != '\0')
  49         {
  50                 hash += symbol[i];
  51                 ++i;
  52         }
  53         hash = hash % HASH_SIZE;
  54         return hash;
  55 }
  56
  57 int add_entry(char symbol[], int address)
  58 {
  59         int hash_val;
  60         hash_val = hash(symbol);
  61         if(symbol_hash[hash_val].name[0] == '\0') /* no entry at this location yet */
  62         {
  63                 strcpy(symbol_hash[hash_val].name, symbol);
  64                 if(address < 0)
  65                 {
  66                         symbol_hash[hash_val].address = ram_address++;
  67                 } else {
  68                         symbol_hash[hash_val].address = address;
  69                 }
  70                 return 1;
  71         } else { /* hash alreay used */
  72
  73                 /* compare value of symbol here with input of function */
  74                 /* this could be a repeat hash */
  75                 if(strcmp(symbol_hash[hash_val].name, symbol) == 0) { return 1; }
  76
  77                 if(next_hash_space() != -1)
  78                 {
  79                         strcpy(symbol_hash[hash_val].name, symbol);
  80                         if(address < 0)
  81                         {
  82                                 symbol_hash[hash_val].address = ram_address++;
  83                         } else {
  84                                 symbol_hash[hash_val].address = address;
  85                         }
  86                         return 1;
  87                 } else {
  88                         print_hash();
  89                         int i = find_line_num();
  90                         line_notification(i);
  91                         exit_error(13, "Symbol table full");
  92                 }
  93         }
  94         return 0;
  95 }
  96
  97 int next_hash_space()
  98 {
  99         int i = -1;
 100         do
 101         {
 102                 ++i;
 103         } while (symbol_hash[i].name[0] != '\0' && i < HASH_SIZE);
 104
 105         if(symbol_hash[i].name[0] == '\0')
 106         {
 107                 return i;
 108         } else {
 109                 return -1;
 110         }
 111 }
 112
 113 int get_address(char symbol[])
 114 {
 115         int hash_val, i = 0, j = 0;
 116         hash_val = hash(symbol);
 117         if(symbol_hash[hash_val].name != NULL)
 118         {
 119                 return symbol_hash[hash_val].address;
 120         } else {
 121                 /*
 122                 could not find hash -- loop through strings
 123                 for length of symbol_hash looking for a match
 124                 */
 125                 while(strcmp(symbol_hash[i].name, symbol) != 0 && j < HASH_SIZE)
 126                 {
 127                         if(i == HASH_SIZE){ i = 0; } else { ++i; }
 128                         ++j;
 129                 }
 130                 if(strcmp(symbol_hash[i].name, symbol) == 0)
 131                 {
 132                         return symbol_hash[i].address;
 133                 }
 134         }
 135         return -1;
 136 }