day 5 part 1

4 files changed, 1245 insertions, 1 deletions

diff --git a/05.c b/05.c
new file mode 100644
index 0000000..b127da7
--- /dev/null
+++ b/05.c
@@ -0,0 +1,98 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "queue.h"
+#include "input.h"
+
+#define INPUT "input/05.txt"
+#define EXPECTED1 70369L
+#define EXPECTED2 203002L
+#define STACK_COUNT 9
+
+void part1(struct input_str* input) {
+	// parse stacks
+	SLIST_HEAD(crate_list, crate) head[STACK_COUNT];
+	struct crate {
+		char crate_char;
+		SLIST_ENTRY(crate) entries;
+	};
+	struct crate* last_crate[STACK_COUNT];
+
+	for(int i = 0; i < STACK_COUNT; i++) {
+		SLIST_INIT(head + i);
+		last_crate[i] = SLIST_FIRST(head + i);
+	}
+
+	size_t line_index = 0;
+	while(input->lines[line_index][0] != '\n' && line_index < input->line_count) {
+		for(int s = 0; s < STACK_COUNT; s++) {
+			int stack_index = 1 + 4 * s;
+			char crate_char = input->lines[line_index][stack_index];
+			if(crate_char == ' ') // stack is empty here
+				continue;
+			struct crate* crate = malloc(sizeof(struct crate));
+			crate->crate_char = crate_char;
+			if(SLIST_EMPTY(head + s))
+				SLIST_INSERT_HEAD(head + s, crate, entries);
+			else
+				SLIST_INSERT_AFTER(last_crate[s], crate, entries);
+			last_crate[s] = crate;
+		}
+		line_index++;
+	}
+	line_index++;
+
+	// parse and execute crate movements
+	for(size_t i = line_index; i < input->line_count; i++) {
+		// parse, as usual copy line before strtok
+		char* line = copy_line(input->lines[i]);
+		//printf("%s\n", line);
+		char* number = strtok(line, " "); // move
+		//printf("%s\n", number);
+		number = strtok(NULL, " ");
+	        int crate_count = atoi(number);
+		strtok(NULL, " "); // from
+		number = strtok(NULL, " ");
+		int from = atoi(number);
+		strtok(NULL, " "); // to
+		number = strtok(NULL, " ");
+		int to = atoi(number);
+		free(line);
+		
+		// now execute
+		//printf("move %d from %d to %d\n", crate_count, from, to);
+		from--;
+		to--;
+		for(int m = 0; m < crate_count; m++) {
+			struct crate* cc = SLIST_FIRST(head + from);
+			SLIST_REMOVE_HEAD(head + from, entries);
+			SLIST_INSERT_HEAD(head + to, cc, entries);
+		}
+	}
+
+	// print result, expected is BSDMQFLSP with my input
+	for(int s = 0; s < STACK_COUNT; s++) {
+		struct crate* cc = SLIST_FIRST(head + s);
+		printf("%c", cc->crate_char);
+	}
+	printf("\n");
+
+	// TODO free all the crates
+}
+
+void part2(struct input_str* input) {
+}
+
+int main() {
+	// read input
+	struct input_str input;
+	input_str_read(&input, INPUT);
+
+	// do stuff
+	part1(&input);
+	part2(&input);
+
+	// cleanup & exit
+	input_str_free(&input);
+	return 0;
+}
diff --git a/Makefile b/Makefile
index 900eb92..aaf2651 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 CC=cc
 CFLAGS=-std=c1x -W -Wall -g -D_GNU_SOURCE
 LDFLAGS=
-EXEC=01 01bis 02 03 04
+EXEC=01 01bis 02 03 04 05
 
 all: $(EXEC)
 
@@ -23,5 +23,8 @@ all: $(EXEC)
 04: input.o 04.o
 	$(CC) -o $@ $^ $(LDFLAGS)
 
+05: input.o 05.o
+	$(CC) -o $@ $^ $(LDFLAGS)
+
 clean:
 	rm -rf *.o $(EXEC)
diff --git a/input/05.txt b/input/05.txt
new file mode 100644
index 0000000..cc0498e
--- /dev/null
+++ b/input/05.txt
@@ -0,0 +1,512 @@
+        [Q] [B]         [H]        
+    [F] [W] [D] [Q]     [S]        
+    [D] [C] [N] [S] [G] [F]        
+    [R] [D] [L] [C] [N] [Q]     [R]
+[V] [W] [L] [M] [P] [S] [M]     [M]
+[J] [B] [F] [P] [B] [B] [P] [F] [F]
+[B] [V] [G] [J] [N] [D] [B] [L] [V]
+[D] [P] [R] [W] [H] [R] [Z] [W] [S]
+ 1   2   3   4   5   6   7   8   9 
+
+move 1 from 4 to 1
+move 2 from 4 to 8
+move 5 from 9 to 6
+move 1 from 1 to 3
+move 5 from 8 to 3
+move 1 from 1 to 5
+move 4 from 3 to 6
+move 14 from 6 to 2
+move 5 from 4 to 5
+move 7 from 7 to 2
+move 24 from 2 to 3
+move 13 from 3 to 2
+move 1 from 7 to 9
+move 1 from 9 to 5
+move 7 from 2 to 6
+move 3 from 1 to 7
+move 3 from 6 to 3
+move 2 from 7 to 1
+move 1 from 7 to 5
+move 2 from 2 to 6
+move 2 from 1 to 4
+move 9 from 5 to 1
+move 1 from 6 to 3
+move 4 from 5 to 4
+move 1 from 2 to 7
+move 4 from 6 to 2
+move 7 from 2 to 3
+move 2 from 2 to 6
+move 2 from 2 to 3
+move 2 from 5 to 4
+move 1 from 7 to 3
+move 4 from 6 to 7
+move 19 from 3 to 6
+move 3 from 7 to 4
+move 1 from 7 to 8
+move 1 from 8 to 1
+move 2 from 1 to 3
+move 10 from 3 to 2
+move 3 from 3 to 8
+move 1 from 3 to 9
+move 1 from 9 to 6
+move 11 from 6 to 8
+move 2 from 3 to 8
+move 6 from 4 to 3
+move 3 from 4 to 1
+move 7 from 2 to 8
+move 1 from 3 to 6
+move 6 from 8 to 5
+move 1 from 4 to 6
+move 9 from 6 to 9
+move 6 from 3 to 8
+move 1 from 3 to 5
+move 10 from 1 to 3
+move 11 from 8 to 7
+move 1 from 3 to 5
+move 1 from 1 to 8
+move 5 from 9 to 2
+move 1 from 6 to 3
+move 5 from 3 to 6
+move 1 from 3 to 5
+move 4 from 6 to 4
+move 1 from 5 to 9
+move 6 from 2 to 4
+move 2 from 2 to 9
+move 5 from 5 to 1
+move 2 from 1 to 7
+move 10 from 8 to 3
+move 1 from 8 to 6
+move 3 from 6 to 3
+move 6 from 4 to 2
+move 8 from 3 to 8
+move 3 from 4 to 8
+move 4 from 2 to 1
+move 3 from 5 to 3
+move 4 from 7 to 6
+move 2 from 9 to 3
+move 1 from 2 to 9
+move 1 from 2 to 3
+move 2 from 4 to 8
+move 1 from 7 to 9
+move 5 from 7 to 8
+move 2 from 7 to 3
+move 14 from 3 to 2
+move 3 from 9 to 5
+move 1 from 3 to 1
+move 1 from 7 to 4
+move 3 from 9 to 8
+move 7 from 8 to 9
+move 7 from 2 to 5
+move 2 from 3 to 7
+move 2 from 7 to 6
+move 16 from 8 to 9
+move 4 from 6 to 5
+move 1 from 2 to 5
+move 21 from 9 to 5
+move 3 from 9 to 3
+move 6 from 1 to 4
+move 1 from 1 to 9
+move 1 from 1 to 4
+move 2 from 6 to 3
+move 3 from 4 to 6
+move 3 from 4 to 8
+move 1 from 9 to 4
+move 2 from 4 to 6
+move 4 from 3 to 6
+move 1 from 3 to 4
+move 1 from 4 to 9
+move 1 from 9 to 8
+move 1 from 8 to 6
+move 6 from 2 to 1
+move 2 from 8 to 4
+move 6 from 1 to 8
+move 23 from 5 to 9
+move 1 from 4 to 7
+move 1 from 7 to 1
+move 22 from 9 to 7
+move 4 from 8 to 7
+move 1 from 5 to 2
+move 1 from 1 to 9
+move 2 from 8 to 4
+move 6 from 6 to 3
+move 2 from 9 to 5
+move 18 from 7 to 4
+move 18 from 4 to 5
+move 1 from 2 to 7
+move 1 from 8 to 4
+move 6 from 7 to 2
+move 5 from 4 to 5
+move 1 from 3 to 1
+move 1 from 7 to 2
+move 4 from 3 to 4
+move 1 from 3 to 4
+move 1 from 1 to 7
+move 1 from 5 to 8
+move 3 from 4 to 3
+move 3 from 3 to 8
+move 2 from 8 to 3
+move 2 from 4 to 8
+move 2 from 7 to 5
+move 1 from 7 to 9
+move 2 from 3 to 1
+move 1 from 9 to 7
+move 4 from 2 to 3
+move 1 from 8 to 9
+move 2 from 1 to 8
+move 2 from 2 to 4
+move 1 from 9 to 1
+move 4 from 6 to 8
+move 1 from 2 to 7
+move 1 from 4 to 7
+move 4 from 8 to 2
+move 1 from 4 to 3
+move 1 from 1 to 9
+move 4 from 8 to 1
+move 2 from 2 to 1
+move 3 from 3 to 9
+move 2 from 7 to 1
+move 32 from 5 to 1
+move 1 from 8 to 7
+move 6 from 5 to 1
+move 2 from 7 to 6
+move 1 from 9 to 5
+move 1 from 3 to 2
+move 1 from 5 to 9
+move 2 from 6 to 1
+move 1 from 3 to 7
+move 1 from 9 to 8
+move 36 from 1 to 4
+move 1 from 8 to 9
+move 5 from 4 to 9
+move 6 from 9 to 3
+move 2 from 2 to 9
+move 3 from 1 to 9
+move 1 from 3 to 2
+move 30 from 4 to 8
+move 1 from 7 to 5
+move 1 from 3 to 5
+move 3 from 3 to 4
+move 2 from 8 to 5
+move 3 from 9 to 8
+move 3 from 9 to 3
+move 19 from 8 to 6
+move 2 from 3 to 5
+move 3 from 4 to 3
+move 1 from 4 to 7
+move 8 from 1 to 8
+move 1 from 3 to 2
+move 1 from 7 to 6
+move 4 from 5 to 3
+move 1 from 1 to 7
+move 2 from 5 to 4
+move 1 from 9 to 4
+move 12 from 6 to 2
+move 1 from 7 to 8
+move 6 from 2 to 9
+move 3 from 6 to 7
+move 2 from 7 to 5
+move 6 from 2 to 3
+move 8 from 3 to 5
+move 5 from 6 to 8
+move 5 from 3 to 6
+move 1 from 9 to 4
+move 1 from 9 to 8
+move 5 from 5 to 9
+move 3 from 4 to 6
+move 1 from 4 to 9
+move 1 from 7 to 5
+move 1 from 3 to 5
+move 8 from 9 to 2
+move 3 from 9 to 6
+move 27 from 8 to 2
+move 10 from 6 to 9
+move 1 from 6 to 4
+move 1 from 4 to 9
+move 2 from 5 to 6
+move 5 from 5 to 3
+move 2 from 6 to 9
+move 5 from 3 to 2
+move 12 from 9 to 3
+move 5 from 3 to 1
+move 3 from 1 to 5
+move 1 from 9 to 8
+move 1 from 5 to 2
+move 1 from 2 to 1
+move 1 from 1 to 6
+move 1 from 5 to 3
+move 34 from 2 to 4
+move 8 from 3 to 9
+move 1 from 6 to 1
+move 1 from 8 to 5
+move 4 from 2 to 8
+move 3 from 8 to 7
+move 1 from 7 to 2
+move 7 from 9 to 8
+move 1 from 9 to 6
+move 2 from 5 to 1
+move 1 from 6 to 9
+move 1 from 9 to 5
+move 2 from 2 to 5
+move 5 from 8 to 6
+move 2 from 8 to 5
+move 1 from 1 to 3
+move 12 from 4 to 6
+move 2 from 7 to 1
+move 4 from 1 to 6
+move 3 from 2 to 3
+move 1 from 8 to 5
+move 1 from 2 to 6
+move 1 from 1 to 9
+move 1 from 9 to 5
+move 16 from 4 to 1
+move 4 from 3 to 1
+move 8 from 1 to 8
+move 1 from 4 to 1
+move 6 from 5 to 8
+move 1 from 5 to 7
+move 12 from 6 to 9
+move 7 from 1 to 5
+move 2 from 1 to 7
+move 1 from 7 to 1
+move 9 from 9 to 6
+move 15 from 6 to 2
+move 2 from 9 to 7
+move 4 from 4 to 5
+move 2 from 2 to 9
+move 3 from 7 to 5
+move 2 from 1 to 3
+move 1 from 7 to 1
+move 10 from 2 to 3
+move 6 from 8 to 6
+move 3 from 9 to 2
+move 14 from 5 to 6
+move 1 from 8 to 4
+move 5 from 8 to 2
+move 2 from 2 to 3
+move 24 from 6 to 1
+move 3 from 1 to 2
+move 9 from 2 to 9
+move 1 from 4 to 3
+move 1 from 4 to 2
+move 1 from 8 to 4
+move 23 from 1 to 4
+move 3 from 2 to 4
+move 2 from 1 to 2
+move 1 from 8 to 4
+move 3 from 3 to 5
+move 3 from 3 to 4
+move 3 from 5 to 8
+move 3 from 2 to 7
+move 2 from 3 to 8
+move 15 from 4 to 3
+move 2 from 4 to 1
+move 19 from 3 to 9
+move 1 from 7 to 2
+move 1 from 2 to 5
+move 1 from 5 to 4
+move 1 from 7 to 6
+move 1 from 7 to 4
+move 3 from 8 to 3
+move 1 from 8 to 4
+move 5 from 3 to 8
+move 1 from 3 to 6
+move 22 from 9 to 2
+move 17 from 2 to 6
+move 3 from 9 to 3
+move 9 from 4 to 9
+move 6 from 4 to 9
+move 5 from 2 to 6
+move 1 from 4 to 2
+move 1 from 4 to 9
+move 1 from 1 to 6
+move 19 from 9 to 2
+move 4 from 8 to 7
+move 1 from 1 to 5
+move 1 from 5 to 3
+move 1 from 8 to 1
+move 1 from 8 to 2
+move 4 from 3 to 7
+move 12 from 6 to 1
+move 3 from 7 to 3
+move 7 from 2 to 7
+move 9 from 2 to 6
+move 4 from 2 to 6
+move 13 from 1 to 4
+move 8 from 6 to 4
+move 16 from 4 to 8
+move 12 from 7 to 6
+move 3 from 8 to 3
+move 1 from 1 to 2
+move 4 from 3 to 8
+move 5 from 8 to 9
+move 27 from 6 to 8
+move 2 from 3 to 7
+move 2 from 2 to 8
+move 2 from 7 to 5
+move 1 from 5 to 9
+move 1 from 5 to 1
+move 1 from 6 to 9
+move 2 from 6 to 2
+move 2 from 2 to 6
+move 2 from 9 to 2
+move 3 from 4 to 3
+move 1 from 1 to 9
+move 5 from 9 to 8
+move 1 from 9 to 5
+move 2 from 2 to 6
+move 2 from 4 to 6
+move 1 from 3 to 7
+move 1 from 5 to 6
+move 1 from 6 to 7
+move 6 from 6 to 8
+move 2 from 7 to 5
+move 2 from 3 to 2
+move 34 from 8 to 1
+move 1 from 5 to 6
+move 1 from 5 to 3
+move 1 from 6 to 1
+move 32 from 1 to 8
+move 23 from 8 to 4
+move 1 from 2 to 1
+move 24 from 8 to 4
+move 1 from 3 to 6
+move 47 from 4 to 6
+move 2 from 6 to 1
+move 3 from 1 to 5
+move 1 from 2 to 1
+move 3 from 5 to 7
+move 21 from 6 to 2
+move 3 from 7 to 8
+move 2 from 1 to 6
+move 8 from 6 to 4
+move 4 from 8 to 9
+move 3 from 2 to 8
+move 4 from 4 to 2
+move 2 from 2 to 5
+move 4 from 9 to 8
+move 2 from 1 to 5
+move 11 from 6 to 1
+move 14 from 2 to 6
+move 2 from 4 to 3
+move 1 from 2 to 9
+move 3 from 2 to 9
+move 20 from 6 to 5
+move 2 from 4 to 2
+move 4 from 9 to 1
+move 8 from 8 to 9
+move 1 from 6 to 9
+move 14 from 5 to 2
+move 10 from 2 to 7
+move 7 from 9 to 6
+move 1 from 6 to 8
+move 6 from 2 to 6
+move 1 from 2 to 5
+move 1 from 3 to 5
+move 9 from 6 to 3
+move 1 from 5 to 2
+move 9 from 7 to 3
+move 12 from 3 to 2
+move 9 from 5 to 9
+move 1 from 8 to 6
+move 3 from 3 to 5
+move 1 from 7 to 6
+move 14 from 2 to 6
+move 3 from 9 to 7
+move 6 from 1 to 2
+move 5 from 1 to 8
+move 10 from 6 to 9
+move 4 from 5 to 6
+move 3 from 2 to 4
+move 9 from 9 to 7
+move 1 from 8 to 7
+move 3 from 9 to 6
+move 3 from 3 to 7
+move 1 from 5 to 1
+move 15 from 7 to 1
+move 2 from 8 to 5
+move 2 from 5 to 4
+move 1 from 7 to 4
+move 1 from 3 to 1
+move 15 from 6 to 7
+move 2 from 4 to 9
+move 3 from 4 to 7
+move 18 from 1 to 6
+move 1 from 8 to 9
+move 6 from 9 to 7
+move 3 from 6 to 8
+move 1 from 1 to 2
+move 2 from 9 to 5
+move 2 from 2 to 9
+move 16 from 6 to 3
+move 15 from 3 to 7
+move 2 from 8 to 4
+move 1 from 3 to 7
+move 3 from 4 to 9
+move 2 from 1 to 9
+move 26 from 7 to 4
+move 1 from 2 to 1
+move 7 from 9 to 8
+move 1 from 2 to 5
+move 2 from 5 to 2
+move 8 from 7 to 5
+move 1 from 7 to 3
+move 1 from 3 to 9
+move 2 from 2 to 7
+move 1 from 6 to 4
+move 4 from 8 to 9
+move 1 from 1 to 3
+move 1 from 5 to 6
+move 2 from 5 to 7
+move 17 from 4 to 9
+move 6 from 4 to 9
+move 1 from 3 to 4
+move 6 from 7 to 9
+move 3 from 5 to 6
+move 2 from 7 to 9
+move 4 from 8 to 9
+move 4 from 6 to 4
+move 8 from 4 to 6
+move 1 from 8 to 4
+move 3 from 5 to 2
+move 2 from 4 to 3
+move 1 from 7 to 9
+move 2 from 3 to 5
+move 4 from 6 to 9
+move 1 from 6 to 1
+move 36 from 9 to 4
+move 2 from 5 to 3
+move 3 from 2 to 1
+move 3 from 1 to 4
+move 14 from 4 to 1
+move 1 from 8 to 5
+move 4 from 1 to 3
+move 5 from 9 to 5
+move 2 from 5 to 8
+move 1 from 8 to 9
+move 4 from 9 to 6
+move 3 from 5 to 8
+move 1 from 5 to 6
+move 2 from 1 to 6
+move 2 from 9 to 7
+move 6 from 6 to 4
+move 1 from 1 to 3
+move 29 from 4 to 6
+move 7 from 3 to 4
+move 1 from 8 to 9
+move 3 from 1 to 6
+move 4 from 1 to 4
+move 1 from 8 to 4
+move 4 from 4 to 3
+move 15 from 6 to 8
+move 9 from 4 to 9
+move 1 from 7 to 9
+move 8 from 8 to 3
+move 3 from 6 to 7
+move 1 from 1 to 2
+move 4 from 7 to 6
+move 7 from 8 to 5
+move 1 from 8 to 4
+move 2 from 5 to 7
+move 1 from 2 to 4
+move 5 from 6 to 1
+move 4 from 3 to 2
diff --git a/queue.h b/queue.h
new file mode 100644
index 0000000..bc1568b
--- /dev/null
+++ b/queue.h
@@ -0,0 +1,631 @@
+/*	$OpenBSD: queue.h,v 1.46 2020/12/30 13:33:12 millert Exp $	*/
+/*	$NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $	*/
+
+/*
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)queue.h	8.5 (Berkeley) 8/20/94
+ */
+
+#ifndef	_SYS_QUEUE_H_
+#define	_SYS_QUEUE_H_
+
+/*
+ * This file defines five types of data structures: singly-linked lists,
+ * lists, simple queues, tail queues and XOR simple queues.
+ *
+ *
+ * A singly-linked list is headed by a single forward pointer. The elements
+ * are singly linked for minimum space and pointer manipulation overhead at
+ * the expense of O(n) removal for arbitrary elements. New elements can be
+ * added to the list after an existing element or at the head of the list.
+ * Elements being removed from the head of the list should use the explicit
+ * macro for this purpose for optimum efficiency. A singly-linked list may
+ * only be traversed in the forward direction.  Singly-linked lists are ideal
+ * for applications with large datasets and few or no removals or for
+ * implementing a LIFO queue.
+ *
+ * A list is headed by a single forward pointer (or an array of forward
+ * pointers for a hash table header). The elements are doubly linked
+ * so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before
+ * or after an existing element or at the head of the list. A list
+ * may only be traversed in the forward direction.
+ *
+ * A simple queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are singly
+ * linked to save space, so elements can only be removed from the
+ * head of the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the
+ * list. A simple queue may only be traversed in the forward direction.
+ *
+ * A tail queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or
+ * after an existing element, at the head of the list, or at the end of
+ * the list. A tail queue may be traversed in either direction.
+ *
+ * An XOR simple queue is used in the same way as a regular simple queue.
+ * The difference is that the head structure also includes a "cookie" that
+ * is XOR'd with the queue pointer (first, last or next) to generate the
+ * real pointer value.
+ *
+ * For details on the use of these macros, see the queue(3) manual page.
+ */
+
+#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
+#define _Q_INVALID ((void *)-1)
+#define _Q_INVALIDATE(a) (a) = _Q_INVALID
+#else
+#define _Q_INVALIDATE(a)
+#endif
+
+/*
+ * Singly-linked List definitions.
+ */
+#define SLIST_HEAD(name, type)						\
+struct name {								\
+	struct type *slh_first;	/* first element */			\
+}
+
+#define	SLIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define SLIST_ENTRY(type)						\
+struct {								\
+	struct type *sle_next;	/* next element */			\
+}
+
+/*
+ * Singly-linked List access methods.
+ */
+#define	SLIST_FIRST(head)	((head)->slh_first)
+#define	SLIST_END(head)		NULL
+#define	SLIST_EMPTY(head)	(SLIST_FIRST(head) == SLIST_END(head))
+#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
+
+#define	SLIST_FOREACH(var, head, field)					\
+	for((var) = SLIST_FIRST(head);					\
+	    (var) != SLIST_END(head);					\
+	    (var) = SLIST_NEXT(var, field))
+
+#define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = SLIST_FIRST(head);				\
+	    (var) && ((tvar) = SLIST_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Singly-linked List functions.
+ */
+#define	SLIST_INIT(head) {						\
+	SLIST_FIRST(head) = SLIST_END(head);				\
+}
+
+#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
+	(elm)->field.sle_next = (slistelm)->field.sle_next;		\
+	(slistelm)->field.sle_next = (elm);				\
+} while (0)
+
+#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
+	(elm)->field.sle_next = (head)->slh_first;			\
+	(head)->slh_first = (elm);					\
+} while (0)
+
+#define	SLIST_REMOVE_AFTER(elm, field) do {				\
+	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;	\
+} while (0)
+
+#define	SLIST_REMOVE_HEAD(head, field) do {				\
+	(head)->slh_first = (head)->slh_first->field.sle_next;		\
+} while (0)
+
+#define SLIST_REMOVE(head, elm, type, field) do {			\
+	if ((head)->slh_first == (elm)) {				\
+		SLIST_REMOVE_HEAD((head), field);			\
+	} else {							\
+		struct type *curelm = (head)->slh_first;		\
+									\
+		while (curelm->field.sle_next != (elm))			\
+			curelm = curelm->field.sle_next;		\
+		curelm->field.sle_next =				\
+		    curelm->field.sle_next->field.sle_next;		\
+	}								\
+	_Q_INVALIDATE((elm)->field.sle_next);				\
+} while (0)
+
+/*
+ * List definitions.
+ */
+#define LIST_HEAD(name, type)						\
+struct name {								\
+	struct type *lh_first;	/* first element */			\
+}
+
+#define LIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define LIST_ENTRY(type)						\
+struct {								\
+	struct type *le_next;	/* next element */			\
+	struct type **le_prev;	/* address of previous next element */	\
+}
+
+/*
+ * List access methods.
+ */
+#define	LIST_FIRST(head)		((head)->lh_first)
+#define	LIST_END(head)			NULL
+#define	LIST_EMPTY(head)		(LIST_FIRST(head) == LIST_END(head))
+#define	LIST_NEXT(elm, field)		((elm)->field.le_next)
+
+#define LIST_FOREACH(var, head, field)					\
+	for((var) = LIST_FIRST(head);					\
+	    (var)!= LIST_END(head);					\
+	    (var) = LIST_NEXT(var, field))
+
+#define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = LIST_FIRST(head);				\
+	    (var) && ((tvar) = LIST_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * List functions.
+ */
+#define	LIST_INIT(head) do {						\
+	LIST_FIRST(head) = LIST_END(head);				\
+} while (0)
+
+#define LIST_INSERT_AFTER(listelm, elm, field) do {			\
+	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
+		(listelm)->field.le_next->field.le_prev =		\
+		    &(elm)->field.le_next;				\
+	(listelm)->field.le_next = (elm);				\
+	(elm)->field.le_prev = &(listelm)->field.le_next;		\
+} while (0)
+
+#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.le_prev = (listelm)->field.le_prev;		\
+	(elm)->field.le_next = (listelm);				\
+	*(listelm)->field.le_prev = (elm);				\
+	(listelm)->field.le_prev = &(elm)->field.le_next;		\
+} while (0)
+
+#define LIST_INSERT_HEAD(head, elm, field) do {				\
+	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
+		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
+	(head)->lh_first = (elm);					\
+	(elm)->field.le_prev = &(head)->lh_first;			\
+} while (0)
+
+#define LIST_REMOVE(elm, field) do {					\
+	if ((elm)->field.le_next != NULL)				\
+		(elm)->field.le_next->field.le_prev =			\
+		    (elm)->field.le_prev;				\
+	*(elm)->field.le_prev = (elm)->field.le_next;			\
+	_Q_INVALIDATE((elm)->field.le_prev);				\
+	_Q_INVALIDATE((elm)->field.le_next);				\
+} while (0)
+
+#define LIST_REPLACE(elm, elm2, field) do {				\
+	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)	\
+		(elm2)->field.le_next->field.le_prev =			\
+		    &(elm2)->field.le_next;				\
+	(elm2)->field.le_prev = (elm)->field.le_prev;			\
+	*(elm2)->field.le_prev = (elm2);				\
+	_Q_INVALIDATE((elm)->field.le_prev);				\
+	_Q_INVALIDATE((elm)->field.le_next);				\
+} while (0)
+
+/*
+ * Simple queue definitions.
+ */
+#define SIMPLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *sqh_first;	/* first element */			\
+	struct type **sqh_last;	/* addr of last next element */		\
+}
+
+#define SIMPLEQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).sqh_first }
+
+#define SIMPLEQ_ENTRY(type)						\
+struct {								\
+	struct type *sqe_next;	/* next element */			\
+}
+
+/*
+ * Simple queue access methods.
+ */
+#define	SIMPLEQ_FIRST(head)	    ((head)->sqh_first)
+#define	SIMPLEQ_END(head)	    NULL
+#define	SIMPLEQ_EMPTY(head)	    (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
+#define	SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
+
+#define SIMPLEQ_FOREACH(var, head, field)				\
+	for((var) = SIMPLEQ_FIRST(head);				\
+	    (var) != SIMPLEQ_END(head);					\
+	    (var) = SIMPLEQ_NEXT(var, field))
+
+#define	SIMPLEQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = SIMPLEQ_FIRST(head);				\
+	    (var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Simple queue functions.
+ */
+#define	SIMPLEQ_INIT(head) do {						\
+	(head)->sqh_first = NULL;					\
+	(head)->sqh_last = &(head)->sqh_first;				\
+} while (0)
+
+#define SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(head)->sqh_first = (elm);					\
+} while (0)
+
+#define SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.sqe_next = NULL;					\
+	*(head)->sqh_last = (elm);					\
+	(head)->sqh_last = &(elm)->field.sqe_next;			\
+} while (0)
+
+#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(listelm)->field.sqe_next = (elm);				\
+} while (0)
+
+#define SIMPLEQ_REMOVE_HEAD(head, field) do {			\
+	if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
+		(head)->sqh_last = &(head)->sqh_first;			\
+} while (0)
+
+#define SIMPLEQ_REMOVE_AFTER(head, elm, field) do {			\
+	if (((elm)->field.sqe_next = (elm)->field.sqe_next->field.sqe_next) \
+	    == NULL)							\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+} while (0)
+
+#define SIMPLEQ_CONCAT(head1, head2) do {				\
+	if (!SIMPLEQ_EMPTY((head2))) {					\
+		*(head1)->sqh_last = (head2)->sqh_first;		\
+		(head1)->sqh_last = (head2)->sqh_last;			\
+		SIMPLEQ_INIT((head2));					\
+	}								\
+} while (0)
+
+/*
+ * XOR Simple queue definitions.
+ */
+#define XSIMPLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *sqx_first;	/* first element */			\
+	struct type **sqx_last;	/* addr of last next element */		\
+	unsigned long sqx_cookie;					\
+}
+
+#define XSIMPLEQ_ENTRY(type)						\
+struct {								\
+	struct type *sqx_next;	/* next element */			\
+}
+
+/*
+ * XOR Simple queue access methods.
+ */
+#define XSIMPLEQ_XOR(head, ptr)	    ((__typeof(ptr))((head)->sqx_cookie ^ \
+					(unsigned long)(ptr)))
+#define	XSIMPLEQ_FIRST(head)	    XSIMPLEQ_XOR(head, ((head)->sqx_first))
+#define	XSIMPLEQ_END(head)	    NULL
+#define	XSIMPLEQ_EMPTY(head)	    (XSIMPLEQ_FIRST(head) == XSIMPLEQ_END(head))
+#define	XSIMPLEQ_NEXT(head, elm, field)    XSIMPLEQ_XOR(head, ((elm)->field.sqx_next))
+
+
+#define XSIMPLEQ_FOREACH(var, head, field)				\
+	for ((var) = XSIMPLEQ_FIRST(head);				\
+	    (var) != XSIMPLEQ_END(head);				\
+	    (var) = XSIMPLEQ_NEXT(head, var, field))
+
+#define	XSIMPLEQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = XSIMPLEQ_FIRST(head);				\
+	    (var) && ((tvar) = XSIMPLEQ_NEXT(head, var, field), 1);	\
+	    (var) = (tvar))
+
+/*
+ * XOR Simple queue functions.
+ */
+#define	XSIMPLEQ_INIT(head) do {					\
+	arc4random_buf(&(head)->sqx_cookie, sizeof((head)->sqx_cookie)); \
+	(head)->sqx_first = XSIMPLEQ_XOR(head, NULL);			\
+	(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first);	\
+} while (0)
+
+#define XSIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.sqx_next = (head)->sqx_first) ==		\
+	    XSIMPLEQ_XOR(head, NULL))					\
+		(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
+	(head)->sqx_first = XSIMPLEQ_XOR(head, (elm));			\
+} while (0)
+
+#define XSIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.sqx_next = XSIMPLEQ_XOR(head, NULL);		\
+	*(XSIMPLEQ_XOR(head, (head)->sqx_last)) = XSIMPLEQ_XOR(head, (elm)); \
+	(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);	\
+} while (0)
+
+#define XSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.sqx_next = (listelm)->field.sqx_next) ==	\
+	    XSIMPLEQ_XOR(head, NULL))					\
+		(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
+	(listelm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm));		\
+} while (0)
+
+#define XSIMPLEQ_REMOVE_HEAD(head, field) do {				\
+	if (((head)->sqx_first = XSIMPLEQ_XOR(head,			\
+	    (head)->sqx_first)->field.sqx_next) == XSIMPLEQ_XOR(head, NULL)) \
+		(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); \
+} while (0)
+
+#define XSIMPLEQ_REMOVE_AFTER(head, elm, field) do {			\
+	if (((elm)->field.sqx_next = XSIMPLEQ_XOR(head,			\
+	    (elm)->field.sqx_next)->field.sqx_next)			\
+	    == XSIMPLEQ_XOR(head, NULL))				\
+		(head)->sqx_last = 					\
+		    XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);		\
+} while (0)
+
+
+/*
+ * Tail queue definitions.
+ */
+#define TAILQ_HEAD(name, type)						\
+struct name {								\
+	struct type *tqh_first;	/* first element */			\
+	struct type **tqh_last;	/* addr of last next element */		\
+}
+
+#define TAILQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).tqh_first }
+
+#define TAILQ_ENTRY(type)						\
+struct {								\
+	struct type *tqe_next;	/* next element */			\
+	struct type **tqe_prev;	/* address of previous next element */	\
+}
+
+/*
+ * Tail queue access methods.
+ */
+#define	TAILQ_FIRST(head)		((head)->tqh_first)
+#define	TAILQ_END(head)			NULL
+#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
+#define TAILQ_LAST(head, headname)					\
+	(*(((struct headname *)((head)->tqh_last))->tqh_last))
+/* XXX */
+#define TAILQ_PREV(elm, headname, field)				\
+	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+#define	TAILQ_EMPTY(head)						\
+	(TAILQ_FIRST(head) == TAILQ_END(head))
+
+#define TAILQ_FOREACH(var, head, field)					\
+	for((var) = TAILQ_FIRST(head);					\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_NEXT(var, field))
+
+#define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = TAILQ_FIRST(head);					\
+	    (var) != TAILQ_END(head) &&					\
+	    ((tvar) = TAILQ_NEXT(var, field), 1);			\
+	    (var) = (tvar))
+
+
+#define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
+	for((var) = TAILQ_LAST(head, headname);				\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_PREV(var, headname, field))
+
+#define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
+	for ((var) = TAILQ_LAST(head, headname);			\
+	    (var) != TAILQ_END(head) &&					\
+	    ((tvar) = TAILQ_PREV(var, headname, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Tail queue functions.
+ */
+#define	TAILQ_INIT(head) do {						\
+	(head)->tqh_first = NULL;					\
+	(head)->tqh_last = &(head)->tqh_first;				\
+} while (0)
+
+#define TAILQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
+		(head)->tqh_first->field.tqe_prev =			\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(head)->tqh_first = (elm);					\
+	(elm)->field.tqe_prev = &(head)->tqh_first;			\
+} while (0)
+
+#define TAILQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.tqe_next = NULL;					\
+	(elm)->field.tqe_prev = (head)->tqh_last;			\
+	*(head)->tqh_last = (elm);					\
+	(head)->tqh_last = &(elm)->field.tqe_next;			\
+} while (0)
+
+#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
+		(elm)->field.tqe_next->field.tqe_prev =			\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(listelm)->field.tqe_next = (elm);				\
+	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
+} while (0)
+
+#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
+	(elm)->field.tqe_next = (listelm);				\
+	*(listelm)->field.tqe_prev = (elm);				\
+	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
+} while (0)
+
+#define TAILQ_REMOVE(head, elm, field) do {				\
+	if (((elm)->field.tqe_next) != NULL)				\
+		(elm)->field.tqe_next->field.tqe_prev =			\
+		    (elm)->field.tqe_prev;				\
+	else								\
+		(head)->tqh_last = (elm)->field.tqe_prev;		\
+	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
+	_Q_INVALIDATE((elm)->field.tqe_prev);				\
+	_Q_INVALIDATE((elm)->field.tqe_next);				\
+} while (0)
+
+#define TAILQ_REPLACE(head, elm, elm2, field) do {			\
+	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)	\
+		(elm2)->field.tqe_next->field.tqe_prev =		\
+		    &(elm2)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm2)->field.tqe_next;		\
+	(elm2)->field.tqe_prev = (elm)->field.tqe_prev;			\
+	*(elm2)->field.tqe_prev = (elm2);				\
+	_Q_INVALIDATE((elm)->field.tqe_prev);				\
+	_Q_INVALIDATE((elm)->field.tqe_next);				\
+} while (0)
+
+#define TAILQ_CONCAT(head1, head2, field) do {				\
+	if (!TAILQ_EMPTY(head2)) {					\
+		*(head1)->tqh_last = (head2)->tqh_first;		\
+		(head2)->tqh_first->field.tqe_prev = (head1)->tqh_last;	\
+		(head1)->tqh_last = (head2)->tqh_last;			\
+		TAILQ_INIT((head2));					\
+	}								\
+} while (0)
+
+/*
+ * Singly-linked Tail queue declarations.
+ */
+#define	STAILQ_HEAD(name, type)						\
+struct name {								\
+	struct type *stqh_first;	/* first element */		\
+	struct type **stqh_last;	/* addr of last next element */	\
+}
+
+#define	STAILQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).stqh_first }
+
+#define	STAILQ_ENTRY(type)						\
+struct {								\
+	struct type *stqe_next;	/* next element */			\
+}
+
+/*
+ * Singly-linked Tail queue access methods.
+ */
+#define	STAILQ_FIRST(head)	((head)->stqh_first)
+#define	STAILQ_END(head)	NULL
+#define	STAILQ_EMPTY(head)	(STAILQ_FIRST(head) == STAILQ_END(head))
+#define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)
+
+#define STAILQ_FOREACH(var, head, field)				\
+	for ((var) = STAILQ_FIRST(head);				\
+	    (var) != STAILQ_END(head);					\
+	    (var) = STAILQ_NEXT(var, field))
+
+#define	STAILQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = STAILQ_FIRST(head);				\
+	    (var) && ((tvar) = STAILQ_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Singly-linked Tail queue functions.
+ */
+#define	STAILQ_INIT(head) do {						\
+	STAILQ_FIRST((head)) = NULL;					\
+	(head)->stqh_last = &STAILQ_FIRST((head));			\
+} while (0)
+
+#define	STAILQ_INSERT_HEAD(head, elm, field) do {			\
+	if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL)	\
+		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
+	STAILQ_FIRST((head)) = (elm);					\
+} while (0)
+
+#define	STAILQ_INSERT_TAIL(head, elm, field) do {			\
+	STAILQ_NEXT((elm), field) = NULL;				\
+	*(head)->stqh_last = (elm);					\
+	(head)->stqh_last = &STAILQ_NEXT((elm), field);			\
+} while (0)
+
+#define	STAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((elm), field)) == NULL)\
+		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
+	STAILQ_NEXT((elm), field) = (elm);				\
+} while (0)
+
+#define STAILQ_REMOVE_HEAD(head, field) do {                            \
+	if ((STAILQ_FIRST((head)) =					\
+	    STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)		\
+		(head)->stqh_last = &STAILQ_FIRST((head));		\
+} while (0)
+
+#define STAILQ_REMOVE_AFTER(head, elm, field) do {                      \
+	if ((STAILQ_NEXT(elm, field) =					\
+	    STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)	\
+		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
+} while (0)
+
+#define	STAILQ_REMOVE(head, elm, type, field) do {			\
+	if (STAILQ_FIRST((head)) == (elm)) {				\
+		STAILQ_REMOVE_HEAD((head), field);			\
+	} else {							\
+		struct type *curelm = (head)->stqh_first;		\
+		while (STAILQ_NEXT(curelm, field) != (elm))		\
+			curelm = STAILQ_NEXT(curelm, field);		\
+		STAILQ_REMOVE_AFTER(head, curelm, field);		\
+	}								\
+} while (0)
+
+#define	STAILQ_CONCAT(head1, head2) do {				\
+	if (!STAILQ_EMPTY((head2))) {					\
+		*(head1)->stqh_last = (head2)->stqh_first;		\
+		(head1)->stqh_last = (head2)->stqh_last;		\
+		STAILQ_INIT((head2));					\
+	}								\
+} while (0)
+
+#define	STAILQ_LAST(head, type, field)					\
+	(STAILQ_EMPTY((head)) ?	NULL :					\
+	        ((struct type *)(void *)				\
+		((char *)((head)->stqh_last) - offsetof(struct type, field))))
+
+#endif	/* !_SYS_QUEUE_H_ */