Add parallel port handling in parallel.c

Implement parallel port support with detection and configuration.
Add LPT port handling in parallel.c
Implement LPT port detection and configuration functions.

Makefile

@@ -8,8 +8,13 @@ OBJCOPY = i386-elf-objcopy
 BUILD_DIR = build
 CROSS_DIR = cross
 DISK_IMG = $(BUILD_DIR)/disk.img
+
+STAGE2_ADDR = 0x7e00
 STAGE2_SIZE = 2048
 
+# Place the memory map (e820) past stage2 bl in memory
+MEMMAP_BASE = $(shell echo $$(($(STAGE2_ADDR) + $(STAGE2_SIZE))))
+
 KERNEL_C_SRC = $(wildcard kernel/*.c)
 KERNEL_ASM_SRC = $(wildcard kernel/*.asm)
 KERNEL_OBJ = $(patsubst kernel/%.c, $(BUILD_DIR)/%.o, $(KERNEL_C_SRC))
@@ -29,7 +34,7 @@ stage1: $(BUILD_DIR)
 # NOTE: Stage2 final size should be checked against `$(STAGE2_SIZE)` by the build system to avoid an overflow.
 # Alternatively, convey the final stage2 size through other means to stage1.
 stage2: $(BUILD_DIR)
-	$(AS) $(ASFLAGS) -o $(BUILD_DIR)/stage2.o bootloader/stage2.asm
+	$(AS) $(ASFLAGS) -DMEMMAP_BASE=$(MEMMAP_BASE) -o $(BUILD_DIR)/stage2.o bootloader/stage2.asm
 	$(CC) -std=c11 -ffreestanding -nostdlib -nostdinc -fno-stack-protector -m32 -Iklibc/include -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
@@ -39,7 +44,7 @@ $(BUILD_DIR)/asm_%.o: kernel/%.asm
 	$(AS) $(ASFLAGS) -o $@ $<
 
 $(BUILD_DIR)/%.o: kernel/%.c
-	$(CC) -std=c11 -ffreestanding -nostdlib -nostdinc -fno-stack-protector -m32 -Iklibc/include -g -c -o $@ $<
+	$(CC) -DMEMMAP_BASE=$(MEMMAP_BASE) -std=c11 -ffreestanding -nostdlib -nostdinc -fno-stack-protector -m32 -Iklibc/include -g -c -o $@ $<
 
 $(BUILD_DIR)/klibc/%.o: klibc/src/%.c
 	$(CC) -std=c11 -ffreestanding -nostdlib -nostdinc -fno-stack-protector -m32 -Iklibc/include -g -c -o $@ $<

bootloader/README.md

@@ -11,16 +11,16 @@ Bootloader documentation for ClassicOS
 
 ## Stage 1 (`stage1.asm`)
 
-Responsible for loading the second stage using BIOS routines, and switching to protected mode.
-
 - Queries CHS parameters from BIOS
 - Loads the second stage bootloader (2048 B) to `0x7c00`
-- Sets up a GDT with descriptor entries for code and data both covering the whole 32-bit address space
 - Enables A20
-- Set CR0.PE (enable protected mode) and jump to stage 2
+- Jumps to stage2
 
 ## Stage 2 (`stage2.asm, stage2_load.c`)
 
+- Read and store E820 memory map from BIOS
+- Sets up a GDT with descriptor entries for code and data both covering the whole 32-bit address space
+- Set CR0.PE (enable protected mode)
 - Set up segment registers
 - Load the kernel ELF header
 - Parse the program headers, and load all `PT_LOAD` segments from disk

bootloader/stage1.asm

@@ -40,11 +40,8 @@ _start:
     call enable_a20
     jc a20_error                ; Jump if A20 enable fails
 
-    ; Setup Global Descriptor Table
-    call setup_gdt
-
-    ; Switch to protected mode and jump to second stage at 0x08:0x7E00
-    call switch_to_pm
+    ; Jump to s2
+    jmp 0x7e00
 
 disk_error:
     mov si, disk_error_msg
@@ -241,30 +238,6 @@ check_a20:
     clc                      ; Clear carry flag to indicate success
     ret
 
-; ----------------------------------------------------------------
-gdt_start:
-    dq 0x0000000000000000         ; Null descriptor
-    dq 0x00CF9A000000FFFF         ; 32-bit code segment (selector 0x08)
-    dq 0x00CF92000000FFFF         ; 32-bit data segment (selector 0x10)
-    dq 0x00009A000000FFFF         ; 16-bit code segment for real mode (selector 0x18)
-
-gdt_descriptor:
-    dw gdt_end - gdt_start - 1
-    dd gdt_start
-gdt_end:
-
-setup_gdt:
-    lgdt [gdt_descriptor]
-    ret
-
-; ----------------------------------------------------------------
-switch_to_pm:
-    cli
-    mov eax, cr0
-    or eax, 1
-    mov cr0, eax
-    jmp 0x08:0x7E00             ; jump to S2
-
 ; ----------------------------------------------------------------
 print_string_16:
 .loop:

bootloader/stage2.asm

@@ -1,10 +1,80 @@
-[BITS 32]
 global _start
-global ata_lba_read
-
 extern load_kernel
 
+%define e820_magic 0x534d4150 ; "SMAP"
+%define e820_entry_size 24
+%define e820_max_entries 128
+
+; ----------------------------------------------------------------
+; Real mode
+; ----------------------------------------------------------------
+[BITS 16]
 _start:
+    call read_e820
+    call setup_gdt
+    call switch_to_pm
+
+read_e820:
+    xor ebx, ebx
+    mov es, bx
+    mov di, MEMMAP_BASE+4       ; ES=0 DI=MEMMAP_BASE+4
+    xor bp, bp                  ; Keeping count in bp
+
+.e820_loop:
+    mov eax, 0xe820
+    mov ecx, e820_entry_size
+    mov edx, e820_magic
+    int 0x15
+    jc .done                    ; Error?
+
+    cmp eax, e820_magic         ; Verify "SMAP"
+    jne .done
+
+    test ecx, ecx               ; Skip 0-sized entries
+    jz .skip
+
+    add di, e820_entry_size     ; Advance write addr
+    inc bp                      ; Increment count
+
+    cmp bp, e820_max_entries    ; Stop if we're at capacity
+    jae .done
+.skip:
+    test ebx, ebx
+    jne .e820_loop
+.done:
+    mov [MEMMAP_BASE], bp       ; Store count
+    ret
+
+setup_gdt:
+    lgdt [gdt_descriptor]
+    ret
+
+switch_to_pm:
+    cli
+    mov eax, cr0
+    or eax, 1
+    mov cr0, eax
+    jmp 0x08:pm_entry
+
+e820_count:
+    dw 0
+
+gdt_start:
+    dq 0x0000000000000000         ; Null descriptor
+    dq 0x00CF9A000000FFFF         ; 32-bit code segment (selector 0x08)
+    dq 0x00CF92000000FFFF         ; 32-bit data segment (selector 0x10)
+    dq 0x00009A000000FFFF         ; 16-bit code segment for real mode (selector 0x18)
+gdt_descriptor:
+    dw gdt_end - gdt_start - 1
+    dd gdt_start
+gdt_end:
+
+; ----------------------------------------------------------------
+; Protected mode
+; ----------------------------------------------------------------
+[BITS 32]
+
+pm_entry:
     ; Set up segments
     ; Data segments
     mov ax, 0x10
@@ -18,9 +88,8 @@ _start:
     mov ax, 0x08
     mov cs, ax
 
-    ; Stack (must be identity-mapped)
+    ; Stack
     mov esp, 0x90000
 
     call load_kernel
-
     jmp eax

kernel/memmap.c

@@ -1,19 +1,16 @@
 #include "memmap.h"
 
+#define BOOTLOADER_MEMMAP_COUNT_ADDR    MEMMAP_BASE
+#define BOOTLOADER_MEMMAP_ADDR          (MEMMAP_BASE + 4)
+
 uint32_t get_memory_map(memory_map_entry_t *map, uint32_t max_entries) {
+    // Read the number of entries found by the bootloader
+    uint32_t entries_found = *(uint32_t*)BOOTLOADER_MEMMAP_COUNT_ADDR;
+    memory_map_entry_t *bios_data = (memory_map_entry_t*)BOOTLOADER_MEMMAP_ADDR;
+
     uint32_t count = 0;
-
-    if (max_entries >= 1) {
-        map[count].base_addr = 0x00000000;
-        map[count].length = 0x0009FC00;
-        map[count].type = 1;
-        count++;
-    }
-
-    if (max_entries >= 2) {
-        map[count].base_addr = 0x00100000;
-        map[count].length = 0x1FF00000;
-        map[count].type = 1;
+    while (count < entries_found && count < max_entries) {
+        map[count] = bios_data[count];
         count++;
     }
 

kernel/memmap.h

@@ -7,6 +7,7 @@ typedef struct {
     uint64_t base_addr;
     uint64_t length;
     uint32_t type;
+    uint32_t ext;
 } __attribute__((packed)) memory_map_entry_t;
 
 uint32_t get_memory_map(memory_map_entry_t *map, uint32_t max_entries);

kernel/parallel.c

@@ -0,0 +1,130 @@
+#include "parallel.h"
+#include "io.h"
+#include "irq.h"
+#include "serial.h"   // or your print/terminal for debug
+
+// Standard PC LPT base addresses
+static const uint16_t lpt_base_addrs[LPT_MAX_PORTS] = {
+    0x378, // LPT1
+    0x278  // LPT2
+};
+
+lpt_device_t lpt_devices[LPT_MAX_PORTS];
+
+// Register offsets
+#define LPT_DATA(base)      (base + 0)
+#define LPT_STATUS(base)    (base + 1)
+#define LPT_CONTROL(base)   (base + 2)
+
+// STATUS bits
+// bit 7: Busy (inverted), 6: Ack, 5: Paper Out, 4: Select, 3: Error
+// CONTROL bits
+// bit 0: Strobe, 1: Auto Linefeed, 2: Init, 3: Select In, 5: Bidirectional (PS/2)
+
+// Simple presence check: write/read control & status
+static bool lpt_detect(uint16_t base) {
+    uint8_t orig_ctrl = inb(LPT_CONTROL(base));
+    outb(LPT_CONTROL(base), orig_ctrl ^ 0x0F);
+    uint8_t new_ctrl = inb(LPT_CONTROL(base));
+    outb(LPT_CONTROL(base), orig_ctrl);
+
+    // If bits changed as expected, port likely exists
+    if (((orig_ctrl ^ new_ctrl) & 0x0F) == 0x0F) {
+        return true;
+    }
+    return false;
+}
+
+static void lpt_configure_bidir(uint16_t base, bool enable) {
+    uint8_t ctrl = inb(LPT_CONTROL(base));
+    if (enable) {
+        ctrl |= (1 << 5);   // Set bidirectional bit (PS/2)
+    } else {
+        ctrl &= ~(1 << 5);
+    }
+    outb(LPT_CONTROL(base), ctrl);
+}
+
+void lpt_set_mode(lpt_port_t port, lpt_mode_t mode) {
+    if (port < 0 || port >= LPT_MAX_PORTS) return;
+    if (!lpt_devices[port].present) return;
+
+    uint16_t base = lpt_devices[port].base;
+
+    switch (mode) {
+        case LPT_MODE_COMPAT:
+            lpt_configure_bidir(base, false);
+            break;
+        case LPT_MODE_BIDIR:
+            lpt_configure_bidir(base, true);
+            break;
+        case LPT_MODE_EPP:
+            // TODO: EPP requires chipset support & config
+            // For now, just enable bidir as a baseline
+            lpt_configure_bidir(base, true);
+            break;
+        case LPT_MODE_ECP:
+            // TODO: ECP requires FIFO, DMA, and ECR register
+            // Stub for future implementation
+            lpt_configure_bidir(base, true);
+            break;
+    }
+
+    lpt_devices[port].mode = mode;
+}
+
+void lpt_write_byte(lpt_port_t port, uint8_t value) {
+    if (port < 0 || port >= LPT_MAX_PORTS) return;
+    if (!lpt_devices[port].present) return;
+
+    uint16_t base = lpt_devices[port].base;
+
+    // Wait until not busy (bit 7 is inverted busy)
+    while (!(inb(LPT_STATUS(base)) & 0x80))
+        ;
+
+    outb(LPT_DATA(base), value);
+
+    // Pulse strobe
+    uint8_t ctrl = inb(LPT_CONTROL(base));
+    outb(LPT_CONTROL(base), ctrl | 0x01);
+    outb(LPT_CONTROL(base), ctrl & ~0x01);
+}
+
+uint8_t lpt_read_byte(lpt_port_t port) {
+    if (port < 0 || port >= LPT_MAX_PORTS) return 0xFF;
+    if (!lpt_devices[port].present) return 0xFF;
+
+    uint16_t base = lpt_devices[port].base;
+
+    // In bidirectional mode, data register is input
+    return inb(LPT_DATA(base));
+}
+
+// IRQ hook: you wire this into your IRQ handler for the LPT IRQ (usually 7 or 5)
+void lpt_irq_handler(lpt_port_t port) {
+    // For now, just a stub. Later:
+    // - read status
+    // - acknowledge interrupt
+    // - wake waiting writer/reader
+    (void)port;
+}
+
+// Initialize all LPT ports
+void lpt_init_all(void) {
+    for (int i = 0; i < LPT_MAX_PORTS; i++) {
+        lpt_devices[i].base = lpt_base_addrs[i];
+        lpt_devices[i].present = lpt_detect(lpt_devices[i].base);
+        lpt_devices[i].mode = LPT_MODE_COMPAT;
+        lpt_devices[i].irq = 0; // You can fill this if you parse BIOS/PCI/ACPI
+
+        if (lpt_devices[i].present) {
+            serial_write("LPT detected at base 0x");
+            // use your print_hex here if you want
+        }
+    }
+
+    // If you want interrupt-driven I/O:
+    // - Map LPT IRQ (usually 7 for LPT1, 5 for LPT2) in your PIC/IRQ layer
+    // - In your IRQ handler, call lpt_irq_handler(port)
+}

kernel/parallel.h

@@ -0,0 +1,40 @@
+#ifndef PARALLEL_H
+#define PARALLEL_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+typedef enum {
+    LPT_PORT_NONE = -1,
+    LPT1_PORT = 0,
+    LPT2_PORT = 1,
+    LPT_MAX_PORTS = 2
+} lpt_port_t;
+
+typedef enum {
+    LPT_MODE_COMPAT = 0,   // Standard (SPP)
+    LPT_MODE_BIDIR,        // PS/2 bidirectional
+    LPT_MODE_EPP,          // IEEE 1284 EPP
+    LPT_MODE_ECP           // IEEE 1284 ECP
+} lpt_mode_t;
+
+typedef struct {
+    uint16_t base;         // Base I/O address (e.g., 0x378, 0x278)
+    bool     present;      // Detected
+    lpt_mode_t mode;       // Current mode
+    uint8_t  irq;          // IRQ line (if known/used)
+} lpt_device_t;
+
+extern lpt_device_t lpt_devices[LPT_MAX_PORTS];
+
+void lpt_init_all(void);
+void lpt_set_mode(lpt_port_t port, lpt_mode_t mode);
+
+// Simple polled I/O
+void lpt_write_byte(lpt_port_t port, uint8_t value);
+uint8_t lpt_read_byte(lpt_port_t port);
+
+// IRQ-driven hook (you implement the handler logic)
+void lpt_irq_handler(lpt_port_t port);
+
+#endif