date and time created 82/01/18 19:21:09 by linton

SCCS-vsn: usr.bin/pascal/pdx/source/source.c 1.1

diff --git a/usr/src/usr.bin/pascal/pdx/source/source.c b/usr/src/usr.bin/pascal/pdx/source/source.c
new file mode 100644 (file)
index 0000000..8bf0a30
--- /dev/null
+++ b/usr/src/usr.bin/pascal/pdx/source/source.c
@@ -0,0 +1,144 @@
+/* Copyright (c) 1982 Regents of the University of California */
+
+static char sccsid[] = "@(#)source.c 1.1 %G%";
+
+/*
+ * source file management
+ */
+
+#include "defs.h"
+#include "source.h"
+
+/*
+ * data structure for indexing source seek addresses by line number
+ *
+ * The constraints are:
+ *
+ *     we want an array so indexing is fast and easy
+ *     we don't want to waste space for small files
+ *     we don't want an upper bound on # of lines in a file
+ *     we don't know how many lines there are
+ *
+ * The solution is a "dirty" hash table.  We have NSLOTS pointers to
+ * arrays of NLINESPERSLOT addresses.  To find the source address of
+ * a particular line we find the slot, allocate space if necessary,
+ * and then find its location within the pointed to array.
+ */
+
+typedef int SEEKADDR;
+
+#define NSLOTS 20
+#define NLINESPERSLOT 500
+
+#define slotno(line)   ((line)/NLINESPERSLOT)
+#define index(line)    ((line)%NLINESPERSLOT)
+#define slot_alloc()   alloc(NLINESPERSLOT, SEEKADDR)
+#define srcaddr(line)  seektab[(line)/NLINESPERSLOT][(line)%NLINESPERSLOT]
+
+LOCAL SEEKADDR *seektab[NSLOTS];
+
+LOCAL FILE *srcfp;
+
+/*
+ * check to make sure a source line number is valid
+ */
+
+chkline(linenum)
+register LINENO linenum;
+{
+       if (linenum < 1) {
+               error("line number must be positive");
+       }
+       if (linenum > lastlinenum) {
+               error("not that many lines");
+       }
+}
+
+/*
+ * print out the given lines from the source
+ */
+
+printlines(l1, l2)
+LINENO l1, l2;
+{
+       register int c;
+       register LINENO i;
+       register FILE *fp;
+
+       chkline(l1);
+       chkline(l2);
+       if (l2 < l1) {
+               error("second line number less than first");
+       }
+       fp = srcfp;
+       fseek(fp, (long) srcaddr(l1), 0);
+       for (i = l1; i <= l2; i++) {
+               printf("%5d   ", i);
+               while ((c = getc(fp)) != '\n') {
+                       putchar(c);
+               }
+               putchar('\n');
+       }
+}
+
+/*
+ * read the source file getting seek pointers for each line
+ */
+
+skimsource(file)
+char *file;
+{
+       register int c;
+       register LINENO count;
+       register FILE *fp;
+       register LINENO linenum;
+       register SEEKADDR lastaddr;
+       register int slot;
+
+       if (file == NIL) {
+               return;
+       }
+       if ((fp = fopen(file, "r")) == NULL) {
+               panic("can't open \"%s\"", file);
+       }
+       if (cursource != NIL) {
+               free_seektab();
+       }
+       cursource = file;
+       linenum = 0, count = 0, lastaddr = 0;
+       while ((c = getc(fp)) != EOF) {
+               count++;
+               if (c == '\n') {
+                       slot = slotno(++linenum);
+                       if (slot >= NSLOTS) {
+                               panic("skimsource: too many lines");
+                       }
+                       if (seektab[slot] == NIL) {
+                               seektab[slot] = slot_alloc();
+                       }
+                       seektab[slot][index(linenum)] = lastaddr;
+                       lastaddr = count;
+               }
+       }
+       lastlinenum = linenum;
+       srcfp = fp;
+}
+
+/*
+ * Erase information and release space in the current seektab.
+ * This is in preparation for reading in seek pointers for a
+ * new file.  It is possible that seek pointers for all files
+ * should be kept around, but the current concern is space.
+ */
+
+LOCAL free_seektab()
+{
+       register int slot;
+
+       for (slot = 0; slot < NSLOTS; slot++) {
+               if (seektab[slot] != NIL) {
+                       free(seektab[slot]);
+                       seektab[slot] = NIL;
+               }
+       }
+}