Initial revision

util/ego/cs/cs_stack.c

@@ -0,0 +1,132 @@
+/*
+ * S T A C K   M O D U L E
+ */
+#include "../share/types.h"
+#include "../share/global.h"
+#include "../share/debug.h"
+#include "../share/aux.h"
+#include "cs.h"
+#include "cs_aux.h"
+
+#define STACK_DEPTH	50
+
+STATIC struct token	Stack[STACK_DEPTH];
+STATIC token_p		free_token;
+
+#define Delete_top()	{--free_token; }
+#define Empty_stack()	{free_token = &Stack[0]; }
+#define Stack_empty()	(free_token == &Stack[0])
+#define Top		(free_token - 1)
+
+Push(tkp)
+	token_p tkp;
+{
+	if (tkp->tk_size == UNKNOWN_SIZE) {
+		Empty_stack(); /* The contents of the Stack is useless. */
+	} else {
+		assert(free_token < &Stack[STACK_DEPTH]);
+
+		free_token->tk_vn = tkp->tk_vn;
+		free_token->tk_size = tkp->tk_size;
+		free_token++->tk_lfirst = tkp->tk_lfirst;
+	}
+}
+
+#define WORD_MULTIPLE(n)	((n / ws) * ws + ( n % ws ? ws : 0 ))
+
+Pop(tkp, size)
+	token_p tkp;
+	offset size;
+{
+	/* Pop a token with given size from the valuenumber stack into tkp. */
+
+	/* First simple case. */
+	if (size != UNKNOWN_SIZE && !Stack_empty() && size == Top->tk_size) {
+		tkp->tk_vn = Top->tk_vn;
+		tkp->tk_size = size;
+		tkp->tk_lfirst = Top->tk_lfirst;
+		Delete_top();
+		return;
+	}
+	/* Now we're in trouble: we must pop something that is not there!
+	 * We just put a dummy into tkp and pop tokens until we've
+	 * popped size bytes.
+	 */
+	/* Create dummy. */
+	tkp->tk_vn = newvalnum();
+	tkp->tk_lfirst = (line_p) 0;
+
+	/* Now fiddle with the Stack. */
+	if (Stack_empty()) return;
+	if (size == UNKNOWN_SIZE) {
+		Empty_stack();
+		return;
+	}
+	if (size > Top->tk_size) {
+		while (!Stack_empty() && size >= Top->tk_size) {
+			size -= Top->tk_size;
+			Delete_top();
+		}
+	}
+	/* Now Stack_empty OR size < Top->tk_size. */
+	if (!Stack_empty()) {
+		if (Top->tk_size - size < ws) {
+			Delete_top();
+		} else {
+			Top->tk_vn = newvalnum();
+			Top->tk_size -= WORD_MULTIPLE(size);
+		}
+	}
+}
+
+Dup(lnp)
+	line_p lnp;
+{
+	/* Duplicate top bytes on the Stack. */
+
+	register token_p bottom = Top;
+	register token_p oldtop = Top;
+	register offset	nbytes = off_set(lnp);
+	struct token dummy;
+
+	/* Find the bottom of the bytes to be duplicated.
+	 * It is possible that we cannot find it.
+	 */
+	while (bottom > &Stack[0] && bottom->tk_size < nbytes) {
+		nbytes -= bottom->tk_size;
+		bottom--;
+	}
+
+	if (bottom < &Stack[0]) {
+		/* There was nothing. */
+		dummy.tk_vn = newvalnum();
+		dummy.tk_size = nbytes;
+		dummy.tk_lfirst = lnp;
+		Push(&dummy);
+	} else {
+		if (bottom->tk_size < nbytes) {
+			/* Not enough, bottom == &Stack[0]. */
+			dummy.tk_vn = newvalnum();
+			dummy.tk_size = nbytes - bottom->tk_size;
+			dummy.tk_lfirst = lnp;
+			Push(&dummy);
+		} else if (bottom->tk_size > nbytes) {
+			/* Not integral # tokens. */
+			dummy.tk_vn = newvalnum();
+			dummy.tk_size = nbytes;
+			dummy.tk_lfirst = lnp;
+			Push(&dummy);
+			bottom++;
+		}
+		/* Bottom points to lowest token to be dupped. */
+		while (bottom <= oldtop) {
+			Push(bottom++);
+			Top->tk_lfirst = lnp;
+		}
+	}
+}
+
+clr_stack()
+{
+	free_token = &Stack[0];
+}