day 21

aoc/arena.c

@@ -6,7 +6,7 @@ arena_init(void *mem, ptrdiff_t size) {
     Arena *arena = mem;
     arena->mem = arena + 1;
     arena->top = arena->mem;
-    arena->lim = arena->mem + size;
+    arena->lim = (char *) mem + size;
     return arena;
 }
 
@@ -15,9 +15,32 @@ align_forward(void *ptr, ptrdiff_t align) {
     return (void *)(((uintptr_t)ptr + align - 1) & ~(align - 1));
 }
 
+static void
+pretty_print_size(char buf[64], ptrdiff_t size) {
+    if (size < 1024) {
+        sprintf(buf, "%ld bytes", size);
+    }
+    else if (size < 1024 * 1024) {
+        sprintf(buf, "%ld KB", size / 1024);
+    }
+    else if (size < 1024 * 1024 * 1024) {
+        sprintf(buf, "%ld MB", size / (1024 * 1024));
+    }
+    else {
+        sprintf(buf, "%ld GB", size / (1024 * 1024 * 1024));
+    }
+}
+
 static void
 arena_oom(Arena *arena, ptrdiff_t size, ptrdiff_t align) {
-    loge("Out of memory in arena %p: requested size %ld, align %ld", arena, size, align);
+    char used[64];
+    pretty_print_size(used, (uintptr_t) arena->top - (uintptr_t) arena->mem);
+    char available[64];
+    pretty_print_size(available, (uintptr_t) arena->lim - (uintptr_t) arena->top);
+    char requested[64];
+    pretty_print_size(requested, size);
+    loge("Out of memory in arena %p: %s used, %s available, %s requested, %ld alignment",
+            arena, used, available, requested, align);
     BP();
 }