From 8858e02afb31b6bbf97c985aea76181f9ba967cc Mon Sep 17 00:00:00 2001
From: Gregory Lirent <opensource@lirent.ru>
Date: Wed, 24 Aug 2022 12:26:17 +0300
Subject: [PATCH] Add implementation of the stack reversion

---
 include/bits/memory.h |  1 +
 src/extra-stack.c     | 48 ++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/include/bits/memory.h b/include/bits/memory.h
index 5750557..5cc4635 100644
--- a/include/bits/memory.h
+++ b/include/bits/memory.h
@@ -16,6 +16,7 @@ extern void  libcdsb_stack_init     (stack_t* stack)                Nonnull__(1)
 extern void  libcdsb_stack_push     (stack_t* stack, void* value)   Nonnull__(1);
 extern void  libcdsb_stack_push_many(stack_t* stack, size_t n, ...) Nonnull__(1);
 extern void* libcdsb_stack_pop      (stack_t* stack)                Nonnull__(1);
+extern void  libcdsb_stack_reverse  (stack_t* stack)                Nonnull__(1);
 extern void  libcdsb_stack_flush    (stack_t* stack)                Nonnull__(1);
 
 extern void* libcdsb_aalloc (size_t a, size_t n) Warn_unused_result__;
diff --git a/src/extra-stack.c b/src/extra-stack.c
index 563a177..bdaca67 100644
--- a/src/extra-stack.c
+++ b/src/extra-stack.c
@@ -27,6 +27,7 @@ void libcdsb_stack_push(stack_t* x, void* value) {
     x->value = value;
 }
 
+
 void libcdsb_stack_push_many(stack_t* x, size_t c, ...) {
 
     va_list args;
@@ -52,6 +53,7 @@ void libcdsb_stack_push_many(stack_t* x, size_t c, ...) {
     va_end(args);
 }
 
+
 void* libcdsb_stack_pop(stack_t* x) {
 
     stack_t* n;
@@ -70,14 +72,50 @@ void* libcdsb_stack_pop(stack_t* x) {
 }
 
 
-void libcdsb_stack_flush(stack_t* stack) {
+void libcdsb_stack_reverse(stack_t* x) {
+
+    stack_t z, *iter, *n, copy;
+
+
+    if (x->prev) {
+        z.prev  = 0;
+        z.value = x->value;
+        iter    = x->prev;
+
+        while (iter->prev) {
+            n = iter;
+            iter = n->prev;
+
+            copy.prev  = z.prev;
+            copy.value = z.value;
+
+            z.prev  = n;
+            z.value = n->value;
+
+            n->prev  = copy.prev;
+            n->value = copy.value;
+        }
+
+        copy.prev  = z.prev;
+        copy.value = z.value;
+
+        x->prev  = iter;
+        x->value = iter->value;
+
+        iter->prev  = copy.prev;
+        iter->value = copy.value;
+    }
+}
+
+
+void libcdsb_stack_flush(stack_t* x) {
     stack_t* c;
 
-    while (stack->prev) {
-        c = stack->prev;
-        stack->prev = c->prev;
+    while (x->prev) {
+        c = x->prev;
+        x->prev = c->prev;
         free(c);
     }
 
-    stack->value = 0;
+    x->value = 0;
 }