1 files changed, 207 insertions, 0 deletions
diff --git a/src/common/strtbl.c b/src/common/strtbl.c
new file mode 100644
index 0000000..129dc94
--- /dev/null
+++ b/src/common/strtbl.c
@@ -0,0 +1,207 @@
+/*
+ * The functions in this file maintain a hash table of strings and manage
+ *   string buffers.
+ */
+#include "../h/gsupport.h"
+
+/*
+ * Prototype for static function.
+ */
+static int streq  (int len, char *s1, char *s2);
+
+/*
+ * Entry in string table.
+ */
+struct str_entry {
+   char *s;                 /* string */
+   int length;              /* length of string */
+   struct str_entry *next;
+   };
+
+#define SBufSize 1024                     /* initial size of a string buffer */
+#define StrTblSz 149                      /* size of string hash table */
+static struct str_entry **str_tbl = NULL; /* string hash table */
+
+/*
+ * init_str - initialize string hash table.
+ */
+void init_str()
+   {
+   int h;
+
+   if (str_tbl == NULL) {
+      str_tbl = alloc(StrTblSz * sizeof(struct str_entry *));
+      for (h = 0; h < StrTblSz; ++h)
+         str_tbl[h] = NULL;
+      }
+   }
+
+/*
+ * free_stbl - free string table.
+ */
+void free_stbl()
+   {
+   struct str_entry *se, *se1;
+   int h;
+
+   for (h = 0; h < StrTblSz; ++h)
+      for (se = str_tbl[h]; se != NULL; se = se1) {
+         se1 = se->next;
+         free((char *)se);
+         }
+
+   free((char *)str_tbl);
+   str_tbl = NULL;
+   }
+
+/*
+ * init_sbuf - initialize a new sbuf struct, allocating an initial buffer.
+ */
+void init_sbuf(sbuf)
+struct str_buf *sbuf;
+   {
+   sbuf->size = SBufSize;
+   sbuf->frag_lst = alloc(sizeof(struct str_buf_frag) + (SBufSize - 1));
+   sbuf->frag_lst->next = NULL;
+   sbuf->strtimage = sbuf->frag_lst->s;
+   sbuf->endimage = sbuf->strtimage;
+   sbuf->end = sbuf->strtimage + SBufSize;
+   }
+
+/*
+ * clear_sbuf - free string buffer storage.
+ */
+void clear_sbuf(sbuf)
+struct str_buf *sbuf;
+   {
+   struct str_buf_frag *sbf, *sbf1;
+
+   for (sbf = sbuf->frag_lst; sbf != NULL; sbf = sbf1) {
+      sbf1 = sbf->next;
+      free((char *)sbf);
+      }
+   sbuf->frag_lst = NULL;
+   sbuf->strtimage = NULL;
+   sbuf->endimage = NULL;
+   sbuf->end = NULL;
+   }
+
+/*
+ * new_sbuf - allocate a new buffer for a sbuf struct, copying the partially
+ *   created string from the end of full buffer to the new one.
+ */
+void new_sbuf(sbuf)
+struct str_buf *sbuf;
+   {
+   struct str_buf_frag *sbf;
+   char *s1, *s2;
+
+   /*
+    * The new buffer is larger than the old one to insure that any
+    *  size string can be buffered.
+    */
+   sbuf->size *= 2;
+   s1 = sbuf->strtimage;
+   sbf = alloc(sizeof(struct str_buf_frag) + (sbuf->size - 1));
+   sbf->next = sbuf->frag_lst;
+   sbuf->frag_lst = sbf;
+   sbuf->strtimage = sbf->s;
+   s2 = sbuf->strtimage;
+   while (s1 < sbuf->endimage)
+      *s2++ = *s1++;
+   sbuf->endimage = s2;
+   sbuf->end = sbuf->strtimage + sbuf->size;
+   }
+
+/*
+ * spec_str - install a special string (null terminated) in the string table.
+ */
+char *spec_str(s)
+char *s;
+   {
+   struct str_entry *se;
+   register char *s1;
+   register int l;
+   register int h;
+
+   h = 0;
+   l = 1;
+   for (s1 = s; *s1 != '\0'; ++s1) {
+      h += *s1 & 0377;
+      ++l;
+      }
+   h %= StrTblSz;
+   for (se = str_tbl[h]; se != NULL; se = se->next)
+      if (l == se->length && streq(l, s, se->s))
+         return se->s;
+   se = NewStruct(str_entry);
+   se->s = s;
+   se->length = l;
+   se->next = str_tbl[h];
+   str_tbl[h] = se;
+   return s;
+   }
+
+/*
+ * str_install - find out if the string at the end of the buffer is in
+ *   the string table. If not, put it there. Return a pointer to the
+ *   string in the table.
+ */
+char *str_install(sbuf)
+struct str_buf *sbuf;
+   {
+   int h;
+   struct str_entry *se;
+   register char *s;
+   register char *e;
+   int l;
+
+   AppChar(*sbuf, '\0');   /* null terminate the buffered copy of the string */
+   s = sbuf->strtimage;
+   e = sbuf->endimage;
+
+   /*
+    * Compute hash value.
+    */
+   h = 0;
+   while (s < e)
+      h += *s++ & 0377;
+   h %= StrTblSz;
+   s = sbuf->strtimage;
+   l = e - s;
+   for (se = str_tbl[h]; se != NULL; se = se->next)
+      if (l == se->length && streq(l, s, se->s)) {
+         /*
+          * A copy of the string is already in the table. Delete the copy
+          *  in the buffer.
+          */
+         sbuf->endimage = s;
+         return se->s;
+         }
+
+   /*
+    * The string is not in the table. Add the copy from the buffer to the
+    *  table.
+    */
+   se = NewStruct(str_entry);
+   se->s = s;
+   se->length = l;
+   sbuf->strtimage = e;
+   se->next = str_tbl[h];
+   str_tbl[h] = se;
+   return se->s;
+   }
+
+/*
+ * streq - compare s1 with s2 for len bytes, and return 1 for equal,
+ *  0 for not equal.
+ */
+static int streq(len, s1, s2)
+register int len;
+register char *s1, *s2;
+   {
+   while (len--)
+      if (*s1++ != *s2++)
+         return 0;
+   return 1;
+   }