From dd5d9e1d48396cbc226ff14fe557a55613c91fcb Mon Sep 17 00:00:00 2001
From: Jon Santmyer <jon@jonsantmyer.com>
Date: Fri, 15 Mar 2024 13:16:02 -0400
Subject: better buddy memory allocator

---
 mem/zone.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 mem/zone.c

(limited to 'mem/zone.c')

diff --git a/mem/zone.c b/mem/zone.c
new file mode 100644
index 0000000..489383a
--- /dev/null
+++ b/mem/zone.c
@@ -0,0 +1,97 @@
+#include "zone.h"
+#include "memory.h"
+#include "boot/boot.h"
+#include "lib/string.h"
+#include "io/log.h"
+
+#define MEM_ZONE_STANDARD_PAGES  (MEM_ZONE_STANDARD_LIMIT >> 12)
+
+static uintmax_t 
+    s_zone_standard_freemap_blocks_flat[BUDDY_BLOCKS_FOR(MEM_ZONE_STANDARD_PAGES)];
+static uintmax_t*
+    s_zone_standard_freemap_blocks[MEM_BUDDY_ORDERS];
+
+static struct PhysicalMemoryZone s_zones[MEM_ZONE_COUNT] = 
+{
+    {
+        .name = "Standard",
+        .base = MEM_ZONE_STANDARD_BASE,
+        .limit = MEM_ZONE_STANDARD_LIMIT,
+        .npages_total = MEM_ZONE_STANDARD_PAGES,
+        .npages_free = 0,
+        .freemap = { 
+            .orders = MEM_BUDDY_ORDERS,
+            .bits = MEM_ZONE_STANDARD_PAGES,
+            .free = 0,
+            .blocks = s_zone_standard_freemap_blocks
+        }
+    },
+    {
+        .name = "Higher",
+        .base = MEM_ZONE_HIGHER_BASE,
+        .limit = -1,
+        .freemap = {
+            .orders = MEM_BUDDY_ORDERS
+        }
+    }
+};
+
+void
+mem_zone_resv(size_t zone, uintptr_t base, uintptr_t limit)
+{
+    size_t base_off = base % PAGESIZE;
+    size_t limit_off = limit % PAGESIZE;
+    
+    if(base_off > 0) base += (PAGESIZE - base_off);
+    limit -= limit_off;
+
+    buddy_mark_range(&s_zones[zone].freemap, base >> 12, limit >> 12);
+}
+
+void
+mem_zone_free(size_t zone, uintptr_t base, uintptr_t limit)
+{
+    size_t base_off = base % PAGESIZE;
+    size_t limit_off = limit % PAGESIZE;
+    
+    if(base_off > 0) base += (PAGESIZE - base_off);
+    limit -= limit_off;
+
+    size_t npages = (limit - base) >> 12;
+    s_zones[zone].npages_free += npages;
+    buddy_free_range(&s_zones[zone].freemap, base >> 12, limit >> 12);
+}
+
+uintptr_t
+mem_zone_alloc(size_t zone, size_t pages)
+{   
+    struct PhysicalMemoryZone *pmz = &s_zones[zone];
+    intmax_t pagei = buddy_alloc(&pmz->freemap, pages);
+    if(pagei < 0) return 0;
+
+    return (((uintmax_t)pagei) << 12) + pmz->base;
+}
+
+void
+mem_zone_setup_standard(void)
+{
+    struct PhysicalMemoryZone *standard_zone = &s_zones[MEM_ZONE_STANDARD];
+    uintmax_t *map_block_layer_base = s_zone_standard_freemap_blocks_flat;
+    for(size_t i = 0; i < MEM_BUDDY_ORDERS; i++) {
+        size_t layer_entries = (standard_zone->freemap.bits / BUDDY_BLOCK_BITS) >> i;
+        standard_zone->freemap.blocks[i] = map_block_layer_base;
+        memset(map_block_layer_base, 0xFF, layer_entries * sizeof(uintmax_t));
+        map_block_layer_base = &map_block_layer_base[layer_entries];
+    }
+
+    for(int i = 0; i < boot_memorymap.count; i++) {
+        struct MemoryMapEntry *entry = &boot_memorymap.entries[i];
+        klogf("%2i\t%#016X -> %#016X (%i)\n",
+                i, entry->base, entry->base + entry->length, entry->usable);
+        if(entry->base > MEM_ZONE_STANDARD_LIMIT) continue;
+        size_t limit = entry->base + entry->length;
+        if(limit > MEM_ZONE_STANDARD_LIMIT) limit = MEM_ZONE_STANDARD_LIMIT;
+        if(entry->usable)
+            mem_zone_free(MEM_ZONE_STANDARD, entry->base, limit);
+    }
+}
-- 
cgit v1.2.1