From bd7889f22a59c567d205c32dc4ffc508b9780121 Mon Sep 17 00:00:00 2001
From: Tom-on64 <kubecekt@gmail.com>
Date: Thu, 25 Apr 2024 19:03:35 +0200
Subject: [PATCH] Added printing memory map

---
 include/string.h |  5 +++++
 src/kernel.c     | 38 ++++++++++++++++++++++++++++++++++++++
 src/stage2.asm   | 23 +++++++++++------------
 3 files changed, 54 insertions(+), 12 deletions(-)

diff --git a/include/string.h b/include/string.h
index e8c282c..aeb80c1 100644
--- a/include/string.h
+++ b/include/string.h
@@ -9,6 +9,11 @@ char* itoa(uint32_t val, uint8_t base) {
 
     if (base == 0 || base > 16) {
         // TODO: Add errors!!
+        return NULL;
+    }
+
+    if (val == 0) {
+        buf[0] = '0';
         return buf;
     }
  
diff --git a/src/kernel.c b/src/kernel.c
index 5edfadf..be15675 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -11,10 +11,18 @@
 
 #define PROMPT "#> "
 
+typedef struct smapEntry_s {
+    uint64_t baseAddress;
+    uint64_t length;
+    uint32_t type;
+    uint32_t acpiAttr;
+} __attribute__ ((packed)) smapEntry_t;
+
 char* filetable = (char*)0x7000; // Pretty sure we don't have to care about the bootloader at 0x7c00
 
 // Function declarations
 void printFiletable(char* ft);
+void printPhysicalMemmap();
 
 void main() {
     // Interrupts
@@ -37,6 +45,8 @@ void main() {
     print("kern.\n\n");
 
     diskRead(5, 1, filetable); // Read the filetable and store it in memory
+    
+    printPhysicalMemmap();
 
     // Run Interactive Shell Program
     // TODO: Make it in another file
@@ -282,3 +292,31 @@ void printFiletable(char* ft) {
     }
 }
 
+void printPhysicalMemmap() {
+    uint32_t entryCount = *(uint32_t*)0x8500;
+    smapEntry_t* smapEntry = (smapEntry_t*)0x8504;
+
+    for (uint32_t i = 0; i < entryCount; i++) {
+        print("Region ");
+        if (i) print(itoa(i, 10));
+        else print("0");
+        print(": base: 0x");
+        print(itoa(smapEntry->baseAddress, 16));
+        print(" length: 0x");
+        print(itoa(smapEntry->length, 16));
+        print(" type: 0x");
+        print(itoa(smapEntry->type, 16));
+
+        switch (smapEntry->type) {
+            case 1: print(" (Available)"); break;
+            case 2: print(" (Reserved)"); break;
+            case 3: print(" (ACPI Reclaim)"); break;
+            case 4: print(" (ACPI NVS)"); break;
+            default: print(" (Reserved)"); break;
+        }
+
+        putc('\n');
+        smapEntry++;
+    }
+}
+
diff --git a/src/stage2.asm b/src/stage2.asm
index 8570419..e100908 100644
--- a/src/stage2.asm
+++ b/src/stage2.asm
@@ -13,7 +13,7 @@ start:
 
 memMapEntries equ 0x8500
 getMemoryMap:
-    mov di, memMapEntries + 4 ; 4 bytes after memMapEntries
+    mov di, 0x8504 ; 4 bytes after memMapEntries
     xor ebx, ebx
     xor bp, bp
     mov edx, "PAMS" ; SMAP in little endian
@@ -26,14 +26,21 @@ getMemoryMap:
     cmp eax, "PAMS"
     jne .error
     test ebx, ebx
-    jz .error
+    jnz .start
+
+.error:
+    mov si, acpiFuncErr
+    call print
+    cli
+    hlt
 
 .nextEntry:
     mov edx, "PAMS" ; In case BIOS messes with edx
     mov ecx, 24
     mov eax, 0xe820
     int 0x15
-    
+
+.start:
     jcxz .skipEntry
     mov ecx, [es:di+8] ; Low 32 bits of length
     or ecx, [es:di+12] ; High 32 bits of length
@@ -48,21 +55,13 @@ getMemoryMap:
     jz .done
     jmp .nextEntry
 
-.error:
-    mov si, acpiFuncErr
-    call print
-    cli
-    hlt
-
 .done:
     mov [memMapEntries], bp
     clc
 
 vbeSetup:
     ; Setup VBE info
-    xor ax, ax
-    mov es, ax
-    mov ah, 0x4f
+    mov ax, 0x4f00
     mov di, vbeInfoBlock
     int 0x10