supercop.ts

commit 27b147c5e407c97b642fe5679b512972871ed81d
parent 71bedc51ed68cfa9be1044ca7663c2980edc011b
Author: finwo <finwo@pm.me>
Date:   Wed, 11 Sep 2019 21:25:54 +0200

free should now work with malloc

Diffstat:
M
lib/c/malloc.c
 | 
53
++++++++++++++++++++++++++++++++++++++++++++++++-----

1 file changed, 48 insertions(+), 5 deletions(-)
diff --git a/lib/c/malloc.c b/lib/c/malloc.c
@@ -1,17 +1,60 @@
+#include "./null.c"
 
 extern unsigned char __heap_base;
 
 unsigned int bump_pointer = &__heap_base;
 
+unsigned int heap_start = &__heap_base;
+unsigned int heap_end   = &__heap_base;
+unsigned int isize      = sizeof(unsigned int);
+unsigned int hsize      = (2 * sizeof(unsigned int));
+
 // TODO: realloc
 // TODO: free
 
 void* malloc(int n) {
-  unsigned int r = bump_pointer;
-  bump_pointer += n;
-  return (void *)r;
+  unsigned int r     = heap_start;
+
+  unsigned int *size = NULL;
+  unsigned int *used = NULL;
+
+  // Loop through known blocks
+  while(r < heap_end) {
+    size = (void*)r;
+    used = (void*)(r+isize);
+
+    // In-use = skip
+    if (*used) {
+      r += *size;
+      continue;
+    }
+
+    // Too small = skip
+    if ((*size) < (n + hsize)) {
+      r += *size;
+      continue;
+    }
+
+    // Take this block
+    *used = n;
+    return (void*)(r + hsize);
+  }
+
+  // Something went wrong
+  if (r < heap_end) {
+    return NULL;
+  }
+
+  // Build a new block
+  size  = (void*)r;
+  used  = (void*)(r+isize);
+  *size = n + hsize;
+  *used = n;
+  heap_end = r + n + hsize;
+  return (void*)(r + hsize);
 }
 
-void free(void* p) {
-  // lol
+void free(void *p) {
+  unsigned int *used = p - isize;
+  *used = 0;
 }