From 13b2bf797bdf4fab0115675c4d2541fff05e285c Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Fri, 4 Feb 2022 18:24:31 -0700
Subject: Implemented new Real-Time friendly Memory Allocation Scheme

---
 src/lib/kmem.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 src/lib/kmem.c

(limited to 'src/lib')

diff --git a/src/lib/kmem.c b/src/lib/kmem.c
new file mode 100644
index 0000000..fc91fc4
--- /dev/null
+++ b/src/lib/kmem.c
@@ -0,0 +1,76 @@
+#include <lib/kmem.h>
+#include <globals.h>
+
+void* kmalloc(unsigned int size)
+{
+	unsigned int sz = 1;
+	while (sz < size && sz < 0x1000)
+		sz *= 2;
+	unsigned long offset = 0x1000*(sz/2);
+	unsigned int exp = 0;
+	unsigned int tmp = sz;
+	while (tmp != 0) {
+		exp++;
+		tmp = tmp >> 1;
+	}
+	unsigned int i = 0;
+	while (i < 0x1000) {
+		if (kmem_lookup[0x1000*exp + i] == 0) {
+			kmem_lookup[0x1000*exp + i] = 1;
+			return (void*)kmem_begin + offset + i*sz;
+		}
+		i++;
+	}
+	return 0;
+}
+
+void* kcalloc(unsigned int size)
+{
+	unsigned char* ptr = kmalloc(size);
+	if (ptr == 0)
+		return 0;
+	for(unsigned int i = 0; i < size; i++)
+		ptr[i] = 0;
+	return ptr;
+}
+
+void* krealloc(void* old, unsigned int size)
+{
+	unsigned long old_size = 1;
+	while (!((unsigned long)kmem_begin + 0x1000*(old_size/2) <= (unsigned long)old && (unsigned long)old < (unsigned long)kmem_begin + 0x1000*old_size))
+		old_size *= 2;
+	if (size <= old_size)
+		return old;
+	void* new = kmalloc(size);
+	if (new == 0)
+		return 0;
+	void* base = (void*)((unsigned long)old - ((unsigned long)old % old_size));
+	void* block_base = kmem_begin + 0x1000*(old_size/2);
+	unsigned int lookup_offset = (base - block_base)/old_size;
+	unsigned int exp = 0;
+	unsigned int tmp = old_size;
+	while (tmp != 0) {
+		exp++;
+		tmp = tmp >> 1;
+	}
+	kmem_lookup[0x1000*exp + lookup_offset] = 0;
+	return new;
+}
+
+void  kfree(void* ptr)
+{
+	unsigned long size = 1;
+	while (!((unsigned long)kmem_begin + 0x1000*(size/2) <= (unsigned long)ptr && (unsigned long)ptr < (unsigned long)kmem_begin + 0x1000*size)) {
+		size *= 2;
+	}
+	void* base = (void*)((unsigned long)ptr - ((unsigned long)ptr % size));
+	void* block_base = kmem_begin + 0x1000*(size/2);
+	unsigned int lookup_offset = (base - block_base)/size;
+	unsigned int exp = 0;
+	unsigned int tmp = size;
+	while (tmp != 0) {
+		exp++;
+		tmp = tmp >> 1;
+	}
+	kmem_lookup[0x1000*exp + lookup_offset] = 0;
+}
-- 
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