From cb605a619b96b9261994f28f4af0f3c7e77f0892 Mon Sep 17 00:00:00 2001
From: Matthew Sotoudeh <matthew@masot.net>
Date: Thu, 16 May 2024 15:46:02 -0700
Subject: test harness includes move_buddy

---
 README                    |  2 +-
 imc/checker.c             | 23 +++++++++++++++++------
 magic_buddy/magic_buddy.c |  3 ++-
 magic_buddy/magic_buddy.h |  2 +-
 4 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/README b/README
index ad827a4..b350f4f 100644
--- a/README
+++ b/README
@@ -65,10 +65,10 @@ Current status of the test harness(es):
     - [X] allocate
     - [X] liberate
     - [X] reallocate
+    - [X] move_buddy
     - [ ] reserve
     - [ ] grow_buddy
     - [ ] shrink_buddy
-    - [ ] move_buddy
 
 ### Usage
 
diff --git a/imc/checker.c b/imc/checker.c
index 2a519ef..2bde59f 100644
--- a/imc/checker.c
+++ b/imc/checker.c
@@ -35,15 +35,26 @@ void check_main() {
     if (choose(2, 0)) pool_size += 11;
     if (choose(2, 0)) pool = (void*)((uint8_t*)pool + 11);
 
-    struct buddy buddy;
+    struct buddy buddy1;
+    struct buddy buddy2;
+    struct buddy *curr_buddy = &buddy1;
     uint8_t magic[MAGIC_COOKIE_BYTES];
     get_random(magic, MAGIC_COOKIE_BYTES);
-    init_buddy(pool, pool_size, magic, &buddy);
+    init_buddy(pool, pool_size, magic, curr_buddy);
 
     size_t size_options[] = {1, 128, 1024, 5, 167, 10500};
     const size_t n_size_options = sizeof(size_options) / sizeof(size_options[0]);
 
     for (int t = 0; t < n_timesteps; t++) {
+        int which_buddy = choose(3, 0);
+        if (which_buddy == 1) {
+            move_buddy(&buddy1, curr_buddy);
+            curr_buddy = &buddy1;
+        } else if (which_buddy == 2) {
+            move_buddy(&buddy2, curr_buddy);
+            curr_buddy = &buddy2;
+        }
+
         // free the regions at this timestep, and ensure its contents are good
         for (struct ll *p = time_to_dielist[t]; p;) {
             for (size_t i = 0; i < p->data_size; i++) {
@@ -56,12 +67,12 @@ void check_main() {
             if (action == n_size_options) {
                 // do a free!
                 struct ll *next = p->next;
-                liberate(p, p->data_size + sizeof(struct ll), &buddy);
+                liberate(p, p->data_size + sizeof(struct ll), curr_buddy);
                 p = next;
             } else if (action == n_size_options + 1) {
                 // do a free, but with reallocate
                 struct ll *next = p->next;
-                p = reallocate(p, p->data_size + sizeof(struct ll), 0, &buddy);
+                p = reallocate(p, 0, p->data_size + sizeof(struct ll), curr_buddy);
                 assert(!p);
                 p = next;
             } else {
@@ -70,7 +81,7 @@ void check_main() {
                 size_t old_size = p->data_size + sizeof(struct ll);
                 p->data_size = size_options[action];
                 size_t new_size = p->data_size + sizeof(struct ll);
-                p = reallocate(p, old_size, new_size, &buddy);
+                p = reallocate(p, new_size, old_size, curr_buddy);
                 for (size_t i = 0; i < p->data_size; i++)
                     p->data[i] = (uint8_t)p->data_size;
                 int lifetime = choose(n_timesteps - t, 0) + 1;
@@ -84,7 +95,7 @@ void check_main() {
 
         // try allocating a region
         size_t size = size_options[choose(n_size_options, 0)];
-        struct ll *ll = allocate(size + sizeof(struct ll), &buddy);
+        struct ll *ll = allocate(size + sizeof(struct ll), curr_buddy);
         if (!ll) continue;
         assert((void*)ll >= pool);
         assert((uint8_t*)ll + size + sizeof(struct ll)
diff --git a/magic_buddy/magic_buddy.c b/magic_buddy/magic_buddy.c
index c6283d8..9deaa8f 100644
--- a/magic_buddy/magic_buddy.c
+++ b/magic_buddy/magic_buddy.c
@@ -197,7 +197,7 @@ static void *_naive_reallocate(void *old, size_t old_size, size_t new_size,
     return new;
 }
 
-void *reallocate(void *old, size_t old_size, size_t new_size,
+void *reallocate(void *old, size_t new_size, size_t old_size,
                  struct buddy *state) {
     if (new_size == 0) return liberate(old, old_size, state), (void*)0;
 
@@ -316,6 +316,7 @@ int shrink_buddy(size_t new_size, struct buddy *state) {
 }
 
 void move_buddy(struct buddy *new_state, struct buddy *old_state) {
+    if (new_state == old_state) return;
     memcpy(new_state, old_state, sizeof(struct buddy));
     for (size_t i = 0; i < ADDRESS_BITS; i++) {
         if (!new_state->avail[i]) continue;
diff --git a/magic_buddy/magic_buddy.h b/magic_buddy/magic_buddy.h
index c8778d6..a25ceb7 100644
--- a/magic_buddy/magic_buddy.h
+++ b/magic_buddy/magic_buddy.h
@@ -30,7 +30,7 @@ void debug_buddy(struct buddy *state);
 
 // Simulates @new = allocate, memcpy(@new, @old), free(@old), with some
 // optimizations for cases where the reallocation can be done in place.
-void *reallocate(void *old, size_t old_size, size_t new_size,
+void *reallocate(void *old, size_t new_size, size_t old_size,
                  struct buddy *state);
 
 // Attempts to reserve a range [@start,@start+@size).
-- 
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