Added very simple stack implementation for procfs

This probably has several bugs, but idc

3 files changed, 147 insertions, 0 deletions

diff --git a/libc/Makefile b/libc/Makefile
index 1a8e0f0..a3d1300 100644
--- a/libc/Makefile
+++ b/libc/Makefile
@@ -10,6 +10,7 @@ COBJS = str.o \
 	cpu.o \
 	sys.o \
 	list.o \
+	stack.o \
 	random.o
 CC = ccache ../cross/opt/bin/i686-elf-gcc
 LD = ccache ../cross/opt/bin/i686-elf-ld
diff --git a/libc/inc/stack.h b/libc/inc/stack.h
new file mode 100644
index 0000000..8fec25f
--- /dev/null
+++ b/libc/inc/stack.h
@@ -0,0 +1,27 @@
+// MIT License, Copyright (c) 2020 Marvin Borner
+
+#ifndef STACK_H
+#define STACK_H
+
+#include <def.h>
+
+struct stack_node {
+	void *data;
+	int nonce;
+	struct stack_node *next;
+	struct stack_node *prev;
+};
+
+struct stack {
+	struct stack_node *tail;
+};
+
+struct stack *stack_new();
+void stack_destroy(struct stack *stack);
+u32 stack_empty(struct stack *stack);
+u32 stack_push_bot(struct stack *stack, void *data);
+u32 stack_push(struct stack *stack, void *data);
+void *stack_pop(struct stack *stack);
+void *stack_peek(struct stack *stack);
+
+#endif
diff --git a/libc/stack.c b/libc/stack.c
new file mode 100644
index 0000000..dac18a2
--- /dev/null
+++ b/libc/stack.c
@@ -0,0 +1,119 @@
+// MIT License, Copyright (c) 2020 Marvin Borner
+
+#include <def.h>
+#include <mem.h>
+#include <stack.h>
+
+static int nonce = 0;
+
+struct stack *stack_new()
+{
+	struct stack *stack = malloc(sizeof(*stack));
+	stack->tail = NULL;
+	return stack;
+}
+
+void stack_destroy(struct stack *stack)
+{
+	struct stack_node *iterator = stack->tail;
+	while (iterator) {
+		if (!iterator->prev) {
+			free(iterator);
+			break;
+		}
+		iterator = iterator->prev;
+		free(iterator->next);
+	}
+	stack->tail = NULL;
+	free(stack);
+	stack = NULL;
+}
+
+struct stack_node *stack_new_node()
+{
+	struct stack_node *node = malloc(sizeof(*node));
+	node->data = NULL;
+	node->prev = NULL;
+	node->next = NULL;
+	node->nonce = nonce++;
+	return node;
+}
+
+u32 stack_push_bot_node(struct stack *stack, struct stack_node *node)
+{
+	if (!stack || !node)
+		return 0;
+
+	if (stack->tail) {
+		struct stack_node *iterator = stack->tail;
+		while (iterator) {
+			if (!iterator->prev)
+				break;
+			iterator = iterator->prev;
+		}
+		iterator->prev = node;
+		node->next = iterator;
+	} else {
+		stack->tail = node;
+	}
+
+	return 1;
+}
+
+u32 stack_push_node(struct stack *stack, struct stack_node *node)
+{
+	if (!stack || !node)
+		return 0;
+
+	if (stack->tail) {
+		stack->tail->next = node;
+		node->prev = stack->tail;
+		stack->tail = node;
+	} else {
+		stack->tail = node;
+	}
+
+	return 1;
+}
+
+u32 stack_empty(struct stack *stack)
+{
+	return !stack->tail;
+}
+
+u32 stack_push_bot(struct stack *stack, void *data)
+{
+	struct stack_node *node = stack_new_node();
+	node->data = data;
+	return stack_push_bot_node(stack, node);
+}
+
+u32 stack_push(struct stack *stack, void *data)
+{
+	struct stack_node *node = stack_new_node();
+	node->data = data;
+	return stack_push_node(stack, node);
+}
+
+void *stack_pop(struct stack *stack)
+{
+	if (!stack || !stack->tail)
+		return NULL;
+
+	struct stack_node *prev = stack->tail;
+
+	stack->tail->prev->next = NULL;
+	stack->tail = stack->tail->prev;
+
+	void *data = prev->data;
+	free(prev);
+	return data;
+}
+
+void *stack_peek(struct stack *stack)
+{
+	if (!stack || !stack->tail)
+		return NULL;
+
+	return stack->tail;
+}