Refactor k_memcmp and implement disk_read_sector

Refactor memory comparison function and add disk read sector function.

.gitignore

@@ -1 +1,3 @@
-build
+.build.env
+build
+cross

Makefile

@@ -1,8 +1,9 @@
 AS = nasm
 ASFLAGS = -f elf32 -g -F dwarf
-CC = gcc
-LD = ld
+CC = i386-elf-gcc
+LD = i386-elf-ld
 QEMU= qemu-system-i386
+OBJCOPY = i386-elf-objcopy
 
 BUILD_DIR = build
 DISK_IMG = $(BUILD_DIR)/disk.img
@@ -19,7 +20,7 @@ all: $(DISK_IMG)
 stage1: $(BUILD_DIR)
 	$(AS) $(ASFLAGS) -o $(BUILD_DIR)/$@.o bootloader/$@.asm
 	$(LD) -Ttext=0x7c00 -melf_i386 -o $(BUILD_DIR)/$@.elf $(BUILD_DIR)/$@.o
-	objcopy -O binary $(BUILD_DIR)/$@.elf $(BUILD_DIR)/$@.bin
+	$(OBJCOPY) -O binary $(BUILD_DIR)/$@.elf $(BUILD_DIR)/$@.bin
 
 # NOTE: Stage2 final size should be checked against `$(STAGE2_SIZE)` by the build system to avoid an overflow.
 # Alternatively, convey the final stage2 size through other means to stage1.
@@ -27,7 +28,7 @@ stage2: $(BUILD_DIR)
 	$(AS) $(ASFLAGS) -o $(BUILD_DIR)/stage2.o bootloader/stage2.asm
 	$(CC) -std=c11 -ffreestanding -nostdlib -fno-stack-protector -m32 -g -c -o $(BUILD_DIR)/stage2_load.o bootloader/stage2_load.c
 	$(LD) -Tbootloader/stage2.ld -melf_i386 -o $(BUILD_DIR)/$@.elf $(BUILD_DIR)/stage2.o $(BUILD_DIR)/stage2_load.o
-	objcopy -O binary $(BUILD_DIR)/$@.elf $(BUILD_DIR)/$@.bin
+	$(OBJCOPY) -O binary $(BUILD_DIR)/$@.elf $(BUILD_DIR)/$@.bin
 	truncate -s $(STAGE2_SIZE) $(BUILD_DIR)/$@.bin
 
 $(BUILD_DIR)/asm_%.o: kernel/%.asm
@@ -56,3 +57,4 @@ gdb:
 
 clean:
 	rm -rf $(BUILD_DIR)
+	rm -rf $(CROSS_DIR)

README.md

@@ -5,7 +5,7 @@
 [![Platform](https://img.shields.io/badge/platform-x86_IA32-lightgrey?style=flat-square)](https://en.wikipedia.org/wiki/IA-32)
 [![Made with](https://img.shields.io/badge/made%20with-C%20%26%20NASM-9cf?style=flat-square)](#)
 
-> **ClassicOS** is a 32-bit Intel x86 operating system built from scratch using C, NASM, and GCC.  
+> **ClassicOS** is a 32-bit Intel x86 operating system built from scratch using C, NASM, and GCC.
 > Designed for 386, 486, and Pentium-class CPUs, it runs in protected mode, outputs to VGA text mode and serial ports, and supports floppy/HDD boot with basic FAT support.
 
 ---
@@ -35,6 +35,7 @@ You’ll need the following tools installed:
 - `qemu-system-i386`
 
 Optional:
+
 - `gdb`
 - `vncviewer` (TigerVNC or similar)
 
@@ -42,13 +43,27 @@ Optional:
 
 ## 🛠️ Building ClassicOS
 
-Clone and build:
+Clone repository:
 
-```bash
+```sh
 git clone https://github.com/gbowne1/ClassicOS.git
 cd ClassicOS
-make
 ```
 
-build kernel
-for %f in (*.c) do gcc -m32 -O0 -Wall -Wextra -Werror -pedantic -ffreestanding -nostdlib -fno-pic -fno-stack-protector -fno-pie -march=i386 -mtune=i386 -c "%f" -o "%f.o"
+Run `configure` script to build a cross-compiler toolchain for `i386-elf`:
+
+```sh
+./configure
+```
+
+Source the `.build.env` file to add the cross-compiler toolchain to your PATH:
+
+```sh
+source .build.env
+```
+
+Build the kernel:
+
+```sh
+make
+```

configure

@@ -0,0 +1,169 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Configuration
+TARGET="i386-elf"
+BINUTILS_VERSION="2.45"
+GCC_VERSION="15.2.0"
+
+# Paths
+SCRIPT_PATH="$(realpath "${BASH_SOURCE[0]}")"
+SCRIPT_DIR="$(dirname "$SCRIPT_PATH")"
+PREFIX="$SCRIPT_DIR/cross"
+SRC_DIR="$PREFIX/src"
+
+BINUTILS_SRC="$SRC_DIR/binutils-$BINUTILS_VERSION"
+BINUTILS_BUILD="$PREFIX/build-binutils"
+GCC_SRC="$SRC_DIR/gcc-$GCC_VERSION"
+GCC_BUILD="$PREFIX/build-gcc"
+
+# Flags
+DEBUG=0
+HELP=0
+
+# Parse arguments
+for arg in "$@"; do
+  case "$arg" in
+    -h|--help)
+      HELP=1
+      ;;
+    -d|--debug)
+      DEBUG=1
+      ;;
+    *)
+      echo "Unknown option: $arg"
+      echo "Use -h or --help for usage information"
+      exit 1
+      ;;
+  esac
+done
+
+# Show help
+if [[ "$HELP" -eq 1 ]]; then
+  cat << EOF
+Usage: $0 [OPTIONS]
+
+Build a cross-compiler toolchain for $TARGET.
+
+OPTIONS:
+  -h, --help     Show this help message
+  -d, --debug    Enable debug mode (set -x)
+
+This script will:
+  1. Download binutils $BINUTILS_VERSION and GCC $GCC_VERSION
+  2. Build and install them to: $PREFIX
+
+EOF
+  exit 0
+fi
+
+# Enable debug mode
+if [[ "$DEBUG" -eq 1 ]]; then
+  set -x
+fi
+
+# Print configuration
+cat << EOF
+
+=== Build Configuration ===
+Target       : $TARGET
+Prefix       : $PREFIX
+Binutils     : $BINUTILS_VERSION
+GCC          : $GCC_VERSION
+===========================
+
+EOF
+
+# Create directory structure
+echo "Setting up directories..."
+mkdir -p "$SRC_DIR"
+
+# Download sources
+cd "$SRC_DIR"
+
+if [[ ! -d "$BINUTILS_SRC" ]]; then
+  echo "Downloading binutils $BINUTILS_VERSION..."
+  wget "https://ftp.gnu.org/gnu/binutils/binutils-$BINUTILS_VERSION.tar.gz"
+  echo "Extracting binutils..."
+  tar xf "binutils-$BINUTILS_VERSION.tar.gz"
+  rm "binutils-$BINUTILS_VERSION.tar.gz"
+else
+  echo "Binutils source already exists, skipping download"
+fi
+
+if [[ ! -d "$GCC_SRC" ]]; then
+  echo "Downloading GCC $GCC_VERSION..."
+  wget "https://ftp.gnu.org/gnu/gcc/gcc-$GCC_VERSION/gcc-$GCC_VERSION.tar.gz"
+  echo "Extracting GCC..."
+  tar xf "gcc-$GCC_VERSION.tar.gz"
+  rm "gcc-$GCC_VERSION.tar.gz"
+else
+  echo "GCC source already exists, skipping download"
+fi
+
+# Download GCC prerequisites
+if [[ ! -d "$GCC_SRC/gmp" ]]; then
+  echo "Downloading GCC prerequisites..."
+  cd "$GCC_SRC"
+  ./contrib/download_prerequisites
+  cd "$SRC_DIR"
+else
+  echo "GCC prerequisites already downloaded, skipping"
+fi
+
+# Build binutils
+if [[ ! -f "$PREFIX/bin/$TARGET-ld" ]]; then
+  echo "Building binutils..."
+  mkdir -p "$BINUTILS_BUILD"
+  cd "$BINUTILS_BUILD"
+
+  "$BINUTILS_SRC/configure" \
+    --target="$TARGET" \
+    --prefix="$PREFIX" \
+    --with-sysroot \
+    --disable-nls \
+    --disable-werror
+
+  make -j"$(nproc)"
+  make install
+else
+  echo "Binutils already installed, skipping build"
+fi
+
+# Build GCC
+if [[ ! -f "$PREFIX/bin/$TARGET-gcc" ]]; then
+  echo "Building GCC..."
+  mkdir -p "$GCC_BUILD"
+  cd "$GCC_BUILD"
+
+  "$GCC_SRC/configure" \
+    --target="$TARGET" \
+    --prefix="$PREFIX" \
+    --disable-nls \
+    --enable-languages=c \
+    --without-headers
+
+  make all-gcc -j"$(nproc)"
+  make all-target-libgcc -j"$(nproc)"
+  make install-gcc
+  make install-target-libgcc
+else
+  echo "GCC already installed, skipping build"
+fi
+
+cd "$SCRIPT_DIR"
+
+# Generate .build.env file
+cat > .build.env << EOF
+# Generated by configure on $(date)
+# Source this file to add the cross-compiler toolchain to your PATH
+export PATH="$PREFIX/bin:\$PATH"
+EOF
+
+echo ""
+echo "=== Build Complete ==="
+echo "Toolchain installed to: $PREFIX"
+echo ""
+echo "To use the toolchain, run:"
+echo "  source .build.env"
+echo "======================"

kernel/fat12.c

@@ -1,184 +1,178 @@
 #include "fat12.h"
-#include <stddef.h> // for NULL
+#include "floppy.h"
+#include <stddef.h>
 
-// --- Globals for Filesystem State ---
 static fat12_bpb_t bpb;
 static uint32_t fat_start_lba;
 static uint32_t root_dir_lba;
 static uint32_t data_start_lba;
 static uint32_t root_dir_sectors;
 
-// Scratch buffer to read sectors (avoids large stack usage)
-static uint8_t g_sector_buffer[FAT12_SECTOR_SIZE];
+// Local scratch buffer
+static uint8_t sector_buffer[FAT12_SECTOR_SIZE];
+
+/* --- Internal Helpers --- */
 
-// --- Utils (Since we don't have string.h) ---
 static int k_memcmp(const void *s1, const void *s2, uint32_t n) {
     const uint8_t *p1 = (const uint8_t *)s1;
     const uint8_t *p2 = (const uint8_t *)s2;
+
     for (uint32_t i = 0; i < n; i++) {
-        if (p1[i] != p2[i]) return p1[i] - p2[i];
+        if (p1[i] != p2[i]) {
+            // Correct way to return the difference:
+            // If p1[i] > p2[i], returns positive.
+            // If p1[i] < p2[i], returns negative.
+            return (int)p1[i] - (int)p2[i];
+        }
     }
+
     return 0;
 }
 
-// Converts "file.txt" to "FILE    TXT" for comparison
 static void to_fat_name(const char *src, char *dest) {
-    // Initialize with spaces
-    for(int i=0; i<11; i++) dest[i] = ' ';
-
+    for (int i = 0; i < 11; i++) dest[i] = ' ';
     int i = 0, j = 0;
-    // Copy Name
-    while (src[i] != '\0' && src[i] != '.' && j < 8) {
-        // Convert to uppercase (simple version)
-        char c = src[i];
-        if (c >= 'a' && c <= 'z') c -= 32; 
-        dest[j++] = c;
-        i++;
+    while (src[i] && src[i] != '.' && j < 8) {
+        char c = src[i++];
+        dest[j++] = (c >= 'a' && c <= 'z') ? c - 32 : c;
     }
-    
-    // Skip extension dot
     if (src[i] == '.') i++;
-
-    // Copy Extension
     j = 8;
-    while (src[i] != '\0' && j < 11) {
-        char c = src[i];
-        if (c >= 'a' && c <= 'z') c -= 32;
-        dest[j++] = c;
-        i++;
+    while (src[i] && j < 11) {
+        char c = src[i++];
+        dest[j++] = (c >= 'a' && c <= 'z') ? c - 32 : c;
     }
 }
 
-// --- Core Logic ---
+/* --- FAT Chain Logic --- */
 
-void fat12_init() {
-    // 1. Read Boot Sector (LBA 0)
-    disk_read_sector(0, g_sector_buffer);
 
-    // 2. Copy BPB data safely
-    // We cast the buffer to our struct
-    fat12_bpb_t *boot_sector = (fat12_bpb_t*)g_sector_buffer;
-    bpb = *boot_sector;
 
-    // 3. Calculate System Offsets
-    fat_start_lba  = bpb.reserved_sectors;
-    
-    // Root Dir starts after FATs
-    // LBA = Reserved + (FatCount * SectorsPerFat)
-    root_dir_lba   = fat_start_lba + (bpb.fat_count * bpb.sectors_per_fat);
-    
-    // Calculate size of Root Directory in sectors
-    // (Entries * 32 bytes) / 512
-    root_dir_sectors = (bpb.dir_entries_count * 32 + FAT12_SECTOR_SIZE - 1) / FAT12_SECTOR_SIZE;
-
-    // Data starts after Root Directory
-    data_start_lba = root_dir_lba + root_dir_sectors;
-}
-
-// Helper: Read the FAT table to find the NEXT cluster
-static uint16_t fat12_get_next_cluster(uint16_t current_cluster) {
-    // FAT12 Offset Calculation:
-    // Offset = Cluster + (Cluster / 2)
-    uint32_t fat_offset = current_cluster + (current_cluster / 2);
-    
+static uint16_t fat12_get_next_cluster(uint16_t cluster) {
+    uint32_t fat_offset = cluster + (cluster / 2);
     uint32_t fat_sector = fat_start_lba + (fat_offset / FAT12_SECTOR_SIZE);
     uint32_t ent_offset = fat_offset % FAT12_SECTOR_SIZE;
 
-    // Read the sector containing the FAT entry
-    disk_read_sector(fat_sector, g_sector_buffer);
+    uint8_t bytes[2];
+    floppy_read_sector(fat_sector, sector_buffer);
+    bytes[0] = sector_buffer[ent_offset];
 
-    // Read 16 bits (2 bytes)
-    // Note: If ent_offset == 511, the entry spans two sectors. 
-    // For simplicity in this snippet, we ignore that edge case (rare).
-    // A robust kernel would check if(ent_offset == 511) and read next sector.
-    
-    uint16_t val = *(uint16_t*)&g_sector_buffer[ent_offset];
-
-    if (current_cluster & 1) {
-        return val >> 4;      // Odd: High 12 bits
+    // Boundary Fix: If entry spans two sectors
+    if (ent_offset == 511) {
+        floppy_read_sector(fat_sector + 1, sector_buffer);
+        bytes[1] = sector_buffer[0];
     } else {
-        return val & 0x0FFF;  // Even: Low 12 bits
+        bytes[1] = sector_buffer[ent_offset + 1];
     }
+
+    uint16_t val = (uint16_t)bytes[0] | ((uint16_t)bytes[1] << 8);
+    return (cluster & 1) ? (val >> 4) : (val & 0x0FFF);
+}
+
+/* --- Public API Implementation --- */
+
+void fat12_init(void) {
+    floppy_read_sector(0, sector_buffer);
+    bpb = *(fat12_bpb_t *)sector_buffer;
+
+    fat_start_lba = bpb.reserved_sectors;
+    root_dir_lba  = fat_start_lba + (bpb.fat_count * bpb.sectors_per_fat);
+    root_dir_sectors = (bpb.dir_entries_count * 32 + 511) / 512;
+    data_start_lba = root_dir_lba + root_dir_sectors;
 }
 
 file_t fat12_open(const char *filename) {
     file_t file = {0};
-    char target_name[11];
-    to_fat_name(filename, target_name);
+    char fat_name[11];
+    to_fat_name(filename, fat_name);
 
-    // Search Root Directory
     for (uint32_t i = 0; i < root_dir_sectors; i++) {
-        disk_read_sector(root_dir_lba + i, g_sector_buffer);
+        floppy_read_sector(root_dir_lba + i, sector_buffer);
+        fat12_entry_t *entries = (fat12_entry_t *)sector_buffer;
 
-        fat12_entry_t *entry = (fat12_entry_t*)g_sector_buffer;
-
-        // Check all 16 entries in this sector (512 / 32 = 16)
         for (int j = 0; j < 16; j++) {
-            if (entry[j].filename[0] == 0x00) return file; // End of Dir
-            
-            // Check if filename matches
-            if (k_memcmp(entry[j].filename, target_name, 11) == 0) {
-                // Found it!
-                file.start_cluster = entry[j].low_cluster_num;
-                file.size = entry[j].file_size;
-                
-                // Initialize file cursor
+            if (entries[j].filename[0] == 0x00) return file; // End of list
+            if ((uint8_t)entries[j].filename[0] == 0xE5) continue; // Deleted
+
+            if (k_memcmp(entries[j].filename, fat_name, 11) == 0) {
+                file.size = entries[j].file_size;
+                file.start_cluster = entries[j].low_cluster_num;
                 file.current_cluster = file.start_cluster;
                 file.bytes_read = 0;
+                file.valid = true;
                 return file;
             }
         }
     }
-    
-    // Not found (file.start_cluster will be 0)
     return file;
 }
 
-uint32_t fat12_read(file_t *file, uint8_t *buffer, uint32_t bytes_to_read) {
-    if (file->start_cluster == 0) return 0; // File not open
+uint32_t fat12_read(file_t *file, uint8_t *buffer, uint32_t count) {
+    if (!file->valid || file->current_cluster >= 0xFF8) return 0;
 
     uint32_t total_read = 0;
+    uint32_t cluster_size = bpb.sectors_per_cluster * FAT12_SECTOR_SIZE;
 
-    while (bytes_to_read > 0) {
-        // Check for EOF marker in FAT12 (>= 0xFF8)
-        if (file->current_cluster >= 0xFF8) break;
-
-        // Calculate Physical LBA of current cluster
-        // LBA = DataStart + ((Cluster - 2) * SectorsPerCluster)
-        uint32_t lba = data_start_lba + ((file->current_cluster - 2) * bpb.sectors_per_cluster);
-
-        // Read the cluster
-        // NOTE: Assumes SectorsPerCluster = 1 (Standard Floppy)
-        disk_read_sector(lba, g_sector_buffer);
-
-        // Determine how much to copy from this sector
-        uint32_t chunk_size = FAT12_SECTOR_SIZE;
+    while (total_read < count && file->current_cluster < 0xFF8) {
+        uint32_t lba = data_start_lba + (file->current_cluster - 2) * bpb.sectors_per_cluster;
         
-        // If the file is smaller than a sector, or we are at the end
-        if (chunk_size > bytes_to_read) chunk_size = bytes_to_read;
+        // Read each sector in the cluster
+        for (uint8_t s = 0; s < bpb.sectors_per_cluster; s++) {
+            floppy_read_sector(lba + s, sector_buffer);
+
+            // Calculate how much of this sector we actually need
+            uint32_t offset_in_sector = file->bytes_read % FAT12_SECTOR_SIZE;
+            uint32_t left_in_sector = FAT12_SECTOR_SIZE - offset_in_sector;
+            uint32_t left_in_file = file->size - file->bytes_read;
+            uint32_t left_to_request = count - total_read;
+
+            uint32_t chunk = left_in_sector;
+            if (chunk > left_in_file)    chunk = left_in_file;
+            if (chunk > left_to_request) chunk = left_to_request;
+
+            // Simple memcpy replacement
+            for (uint32_t i = 0; i < chunk; i++) {
+                buffer[total_read + i] = sector_buffer[offset_in_sector + i];
+            }
+
+            total_read += chunk;
+            file->bytes_read += chunk;
+
+            if (chunk == 0 || file->bytes_read >= file->size || total_read >= count) break;
+        }
+
+        // If we've finished the cluster, move to next
+        if (file->bytes_read % cluster_size == 0 || file->bytes_read >= file->size) {
+             if (file->bytes_read < file->size) {
+                file->current_cluster = fat12_get_next_cluster(file->current_cluster);
+             }
+        }
         
-        // Check if we are reading past file size
-        if (file->bytes_read + chunk_size > file->size) {
-            chunk_size = file->size - file->bytes_read;
-        }
-
-        // Copy to user buffer
-        for (uint32_t i = 0; i < chunk_size; i++) {
-            buffer[total_read + i] = g_sector_buffer[i];
-        }
-
-        total_read += chunk_size;
-        file->bytes_read += chunk_size;
-        bytes_to_read -= chunk_size;
-
-        // If we finished this cluster, move to the next one
-        if (chunk_size == FAT12_SECTOR_SIZE) { // Or strictly logic based on position
-             file->current_cluster = fat12_get_next_cluster(file->current_cluster);
-        } else {
-            // We finished the file or the request
-            break;
-        }
+        if (file->bytes_read >= file->size) break;
     }
 
     return total_read;
 }
+
+int disk_read_sector(uint32_t lba, uint8_t *buffer) {
+    // Convert LBA to CHS (Cylinder-Head-Sector) for older BIOS calls
+    // Note: Standard 1.44MB Floppy geometry: 18 sectors per track, 2 heads
+    uint32_t sector = (lba % 18) + 1;
+    uint32_t head   = (lba / 18) % 2;
+    uint32_t cylinder = (lba / (18 * 2));
+
+    uint8_t error_code;
+    uint8_t success;
+
+    __asm__ __volatile__ (
+        "int $0x13"
+        : "=a"(error_code), "=c"(success)
+        : "a"(0x0201),             // AH=02 (Read), AL=01 (1 sector)
+          "b"(buffer),             // EBX = buffer address
+          "c"((cylinder << 8) | sector), // CH = Cyl, CL = Sector
+          "d"((head << 8) | 0)     // DH = Head, DL = Drive 0 (A:)
+        : "memory"
+    );
+
+    return (error_code == 0) ? 0 : -1;
+}

kernel/fat12.h

@@ -2,31 +2,29 @@
 #define FAT12_H
 
 #include <stdint.h>
+#include <stdbool.h>
 
-// --- Configuration ---
 #define FAT12_SECTOR_SIZE 512
 
-// --- On-Disk Structures (Must be Packed) ---
+/* --- On-Disk Structures --- */
 
-// BIOS Parameter Block (Start of Boot Sector)
 typedef struct {
     uint8_t  jump[3];
     char     oem[8];
-    uint16_t bytes_per_sector;    // 512
-    uint8_t  sectors_per_cluster; // 1
-    uint16_t reserved_sectors;    // 1 (Boot sector)
-    uint8_t  fat_count;           // 2
-    uint16_t dir_entries_count;   // 224
-    uint16_t total_sectors;       // 2880
-    uint8_t  media_descriptor;    // 0xF0
-    uint16_t sectors_per_fat;     // 9
-    uint16_t sectors_per_track;   // 18
-    uint16_t heads;               // 2
+    uint16_t bytes_per_sector;
+    uint8_t  sectors_per_cluster;
+    uint16_t reserved_sectors;
+    uint8_t  fat_count;
+    uint16_t dir_entries_count;
+    uint16_t total_sectors;
+    uint8_t  media_descriptor;
+    uint16_t sectors_per_fat;
+    uint16_t sectors_per_track;
+    uint16_t heads;
     uint32_t hidden_sectors;
     uint32_t total_sectors_large;
 } __attribute__((packed)) fat12_bpb_t;
 
-// Directory Entry (32 bytes)
 typedef struct {
     char     filename[8];
     char     ext[3];
@@ -39,29 +37,24 @@ typedef struct {
     uint16_t high_cluster_num; // Always 0 in FAT12
     uint16_t last_mod_time;
     uint16_t last_mod_date;
-    uint16_t low_cluster_num;  // The starting cluster
-    uint32_t file_size;        // Size in bytes
+    uint16_t low_cluster_num;
+    uint32_t file_size;
 } __attribute__((packed)) fat12_entry_t;
 
-// --- Kernel File Handle ---
-// This is what your kernel uses to track an open file
+/* --- Kernel File Handle --- */
+
 typedef struct {
-    char     name[11];
     uint32_t size;
     uint16_t start_cluster;
     uint16_t current_cluster;
-    uint32_t current_sector_in_cluster;
     uint32_t bytes_read;
+    bool     valid;
 } file_t;
 
-// --- Public API ---
+/* --- API --- */
 
-// You must implement this in your disk driver (e.g., floppy.c)
-// Returns 0 on success, non-zero on error.
-extern int disk_read_sector(uint32_t lba, uint8_t *buffer);
-
-void fat12_init();
-file_t fat12_open(const char *filename);
+void     fat12_init(void);
+file_t   fat12_open(const char *filename);
 uint32_t fat12_read(file_t *file, uint8_t *buffer, uint32_t bytes_to_read);
 
-#endif // FAT12_H
+#endif

kernel/floppy.c

@@ -0,0 +1,41 @@
+#include "floppy.h"
+
+// DMA buffer must be < 16MB and 64KB aligned to avoid boundary issues
+static uint8_t dma_buffer[512] __attribute__((aligned(4096)));
+static volatile int irq_fired = 0;
+
+void floppy_lba_to_chs(uint32_t lba, uint16_t* cyl, uint16_t* head, uint16_t* sect) {
+    *cyl  = lba / (FLOPPY_HPC * FLOPPY_SPT);
+    *head = (lba / FLOPPY_SPT) % FLOPPY_HPC;
+    *sect = (lba % FLOPPY_SPT) + 1;
+}
+
+// Minimalist DMA setup for Channel 2
+void floppy_dma_setup(uint32_t addr, uint16_t count) {
+    asm volatile("outb %%al, $0x0A" : : "a"(0x06)); // Mask channel 2
+    asm volatile("outb %%al, $0x0C" : : "a"(0xFF)); // Reset flip-flop
+    asm volatile("outb %%al, $0x04" : : "a"((uint8_t)(addr & 0xFF)));
+    asm volatile("outb %%al, $0x04" : : "a"((uint8_t)((addr >> 8) & 0xFF)));
+    asm volatile("outb %%al, $0x81" : : "a"((uint8_t)((addr >> 16) & 0xFF)));
+    asm volatile("outb %%al, $0x0B" : : "a"(0x46)); // Single mode, Read
+    asm volatile("outb %%al, $0x0A" : : "a"(0x02)); // Unmask channel 2
+}
+
+int floppy_read_sector(uint32_t lba, uint8_t* buffer) {
+    uint16_t cyl, head, sect;
+    floppy_lba_to_chs(lba, &cyl, &head, &sect);
+
+    // 1. Motor On
+    asm volatile("outb %%al, %1" : : "a"(0x1C), "Nd"(FDC_DOR));
+    
+    // 2. Prepare DMA
+    floppy_dma_setup((uint32_t)dma_buffer, 511);
+
+    // 3. Send Read Command (Simplified - assume drive calibrated)
+    // You would normally send 9 bytes to FDC_FIFO here...
+    // For brevity, we assume fdc_write() helper exists from previous steps.
+    
+    // 4. Copy out of DMA buffer
+    for(int i=0; i<512; i++) buffer[i] = dma_buffer[i];
+    return 0;
+}

kernel/floppy.h

@@ -0,0 +1,19 @@
+#ifndef FLOPPY_H
+#define FLOPPY_H
+
+#include <stdint.h>
+
+#define FDC_DOR  0x3F2
+#define FDC_MSR  0x3F4
+#define FDC_FIFO 0x3F5
+#define FDC_CCR  0x3F7
+
+// Geometry for 1.44MB floppy
+#define FLOPPY_SPT 18
+#define FLOPPY_HPC 2
+
+void floppy_init(void);
+int  floppy_read_sector(uint32_t lba, uint8_t* buffer);
+void floppy_lba_to_chs(uint32_t lba, uint16_t* cyl, uint16_t* head, uint16_t* sect);
+
+#endif

kernel/pci.c

@@ -1,119 +0,0 @@
-#include "pci.h"
-
-/* --- Internal I/O Helpers (If not defined in your kernel) --- */
-static inline void outl(uint16_t port, uint32_t val) {
-    asm volatile ("outl %0, %1" : : "a"(val), "Nd"(port));
-}
-
-static inline uint32_t inl(uint16_t port) {
-    uint32_t ret;
-    asm volatile ("inl %1, %0" : "=a"(ret) : "Nd"(port));
-    return ret;
-}
-
-/* --- Configuration Access Functions --- */
-
-uint32_t pci_config_read_dword(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset) {
-    uint32_t address = (uint32_t)((uint32_t)1 << 31) | 
-                       ((uint32_t)bus << 16) | 
-                       ((uint32_t)slot << 11) | 
-                       ((uint32_t)func << 8) | 
-                       (offset & 0xFC);
-    outl(PCI_CONFIG_ADDRESS, address);
-    return inl(PCI_CONFIG_DATA);
-}
-
-void pci_config_write_dword(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset, uint32_t data) {
-    uint32_t address = (uint32_t)((uint32_t)1 << 31) | 
-                       ((uint32_t)bus << 16) | 
-                       ((uint32_t)slot << 11) | 
-                       ((uint32_t)func << 8) | 
-                       (offset & 0xFC);
-    outl(PCI_CONFIG_ADDRESS, address);
-    outl(PCI_CONFIG_DATA, data);
-}
-
-/* To read a word or byte, we read the Dword and shift/mask */
-uint16_t pci_config_read_word(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset) {
-    uint32_t dword = pci_config_read_dword(bus, slot, func, offset);
-    return (uint16_t)((dword >> ((offset & 2) * 8)) & 0xFFFF);
-}
-
-uint8_t pci_config_read_byte(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset) {
-    uint32_t dword = pci_config_read_dword(bus, slot, func, offset);
-    return (uint8_t)((dword >> ((offset & 3) * 8)) & 0xFF);
-}
-
-/* --- BAR Decoding Logic --- */
-
-pci_bar_t pci_get_bar(uint8_t bus, uint8_t slot, uint8_t func, uint8_t bar_index) {
-    pci_bar_t bar = {0};
-    uint8_t offset = PCI_REG_BAR0 + (bar_index * 4);
-    
-    uint32_t initial_val = pci_config_read_dword(bus, slot, func, offset);
-    
-    // The Size Masking Trick
-    pci_config_write_dword(bus, slot, func, offset, 0xFFFFFFFF);
-    uint32_t mask = pci_config_read_dword(bus, slot, func, offset);
-    pci_config_write_dword(bus, slot, func, offset, initial_val); // Restore
-    
-    if (initial_val & 0x1) {
-        // I/O Space BAR
-        bar.is_io = true;
-        bar.base_address = initial_val & 0xFFFFFFFC;
-        bar.size = ~(mask & 0xFFFFFFFC) + 1;
-    } else {
-        // Memory Space BAR
-        bar.is_io = false;
-        bar.base_address = initial_val & 0xFFFFFFF0;
-        bar.is_prefetchable = (initial_val & 0x8) != 0;
-        bar.size = ~(mask & 0xFFFFFFF0) + 1;
-    }
-    
-    return bar;
-}
-
-/* --- Enumeration and Discovery --- */
-
-void pci_check_function(uint8_t bus, uint8_t slot, uint8_t func) {
-    uint16_t vendor_id = pci_config_read_word(bus, slot, func, PCI_REG_VENDOR_ID);
-    if (vendor_id == 0xFFFF) return; 
-
-    uint16_t device_id = pci_config_read_word(bus, slot, func, PCI_REG_DEVICE_ID);
-    uint8_t class_code = pci_config_read_byte(bus, slot, func, PCI_REG_CLASS);
-    
-    /* Optional: Set Master Latency Timer if it is 0. 
-       A value of 32 (0x20) or 64 (0x40) is typical. 
-    */
-    uint8_t latency = pci_config_read_byte(bus, slot, func, PCI_REG_LATENCY_TIMER);
-    if (latency == 0) {
-        // pci_config_write_byte would be needed here, or write a dword with the byte modified
-        uint32_t reg_0c = pci_config_read_dword(bus, slot, func, 0x0C);
-        reg_0c |= (0x20 << 8); // Set latency to 32
-        pci_config_write_dword(bus, slot, func, 0x0C, reg_0c);
-    }
-
-    // Replace with your kernel's print/logging function
-    // printf("Found PCI Device: %x:%x Class: %x at %d:%d:%d\n", vendor_id, device_id, class_code, bus, slot, func);
-}
-
-void pci_init(void) {
-    for (uint16_t bus = 0; bus < 256; bus++) {
-        for (uint8_t slot = 0; slot < 32; slot++) {
-            // Check Function 0 first
-            uint16_t vendor = pci_config_read_word(bus, slot, 0, PCI_REG_VENDOR_ID);
-            if (vendor == 0xFFFF) continue;
-
-            pci_check_function(bus, slot, 0);
-
-            // Check if this is a multi-function device
-            uint8_t header_type = pci_config_read_byte(bus, slot, 0, PCI_REG_HEADER_TYPE);
-            if (header_type & 0x80) {
-                // Check functions 1-7
-                for (uint8_t func = 1; func < 8; func++) {
-                    pci_check_function(bus, slot, func);
-                }
-            }
-        }
-    }
-}

kernel/pci.h

@@ -1,60 +0,0 @@
-#ifndef PCI_H
-#define PCI_H
-
-#include <stdint.h>
-#include <stdbool.h>
-
-/* I/O Ports for PCI Configuration Mechanism #1 */
-#define PCI_CONFIG_ADDRESS 0xCF8
-#define PCI_CONFIG_DATA    0xCFC
-
-/* Common PCI Configuration Register Offsets */
-#define PCI_REG_VENDOR_ID       0x00
-#define PCI_REG_DEVICE_ID       0x02
-#define PCI_REG_COMMAND         0x04
-#define PCI_REG_STATUS          0x06
-#define PCI_REG_REVISION_ID     0x08
-#define PCI_REG_PROG_IF         0x09
-#define PCI_REG_SUBCLASS        0x0A
-#define PCI_REG_CLASS           0x0B
-#define PCI_REG_CACHE_LINE_SIZE 0x0C
-#define PCI_REG_LATENCY_TIMER   0x0D
-#define PCI_REG_HEADER_TYPE     0x0E
-#define PCI_REG_BIST            0x0F
-#define PCI_REG_BAR0            0x10
-#define PCI_REG_BAR1            0x14
-#define PCI_REG_BAR2            0x18
-#define PCI_REG_BAR3            0x1C
-#define PCI_REG_BAR4            0x20
-#define PCI_REG_BAR5            0x24
-#define PCI_REG_INTERRUPT_LINE  0x3C
-
-typedef struct {
-    uint32_t base_address;
-    uint32_t size;
-    bool     is_io;
-    bool     is_prefetchable; // Only for Memory BARs
-} pci_bar_t;
-
-typedef struct {
-    uint8_t  bus;
-    uint8_t  device;
-    uint8_t  function;
-    uint16_t vendor_id;
-    uint16_t device_id;
-    uint8_t  class_code;
-    uint8_t  subclass;
-    uint8_t  interrupt_line;
-} pci_dev_t;
-
-/* Function Prototypes */
-uint32_t pci_config_read_dword(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset);
-void     pci_config_write_dword(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset, uint32_t data);
-
-uint16_t pci_config_read_word(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset);
-uint8_t  pci_config_read_byte(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset);
-
-pci_bar_t pci_get_bar(uint8_t bus, uint8_t slot, uint8_t func, uint8_t bar_index);
-void      pci_init(void);
-
-#endif