From 781029e00ad1efb141eb77e3f72f03f33bc03ce6 Mon Sep 17 00:00:00 2001
From: Alexander Myltsev <a.myltsev@gmail.com>
Date: Tue, 13 Dec 2022 01:18:30 +0300
Subject: [PATCH] Support the "halt" command.

---
 drivers/keyboard.c | 19 ++++++++++++++-----
 drivers/keyboard.h |  3 +++
 fs/fs.c            |  8 ++++++--
 kernel.c           | 16 +++++++++++++---
 4 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/drivers/keyboard.c b/drivers/keyboard.c
index 8de3bec..f64a084 100644
--- a/drivers/keyboard.c
+++ b/drivers/keyboard.c
@@ -5,20 +5,29 @@
 
 static const char sc_ascii[] = {
     '?', '?', '1', '2', '3', '4', '5', '6',
-    '7', '8', '9', '0', '-', '=', '?', '?', 'Q', 'W', 'E', 'R', 'T', 'Y',
-    'U', 'I', 'O', 'P', '[', ']', '?', '?', 'A', 'S', 'D', 'F', 'G',
-    'H', 'J', 'K', 'L', ';', '\'', '`', '?', '\\', 'Z', 'X', 'C', 'V',
-    'B', 'N', 'M', ',', '.', '/', '?', '?', '?', ' ',
+    '7', '8', '9', '0', '-', '=', '?', '?', 'q', 'w', 'e', 'r', 't', 'y',
+    'u', 'i', 'o', 'p', '[', ']', '\n', '?', 'a', 's', 'd', 'f', 'g',
+    'h', 'j', 'k', 'l', ';', '\'', '`', '?', '\\', 'z', 'x', 'c', 'v',
+    'b', 'n', 'm', ',', '.', '/', '?', '?', '?', ' ',
 };
 
 static void interrupt_handler(registers_t *r) {
     uint8_t scancode = port_byte_in(0x60);
     if (scancode < sizeof(sc_ascii)) {
-        char string[] = {sc_ascii[scancode], '\0'};
+        char c = sc_ascii[scancode];
+        if (kbd_buf_size < 1024) {
+            kbd_buf[kbd_buf_size++] = c;
+        }
+        char string[] = {c, '\0'};
         printk(string);
     }
 }
 
+char* kbd_buf;
+unsigned kbd_buf_size;
+
 void init_keyboard() {
+    kbd_buf = (char*)(1 << 20);
+
     register_interrupt_handler(IRQ1, interrupt_handler);
 }
diff --git a/drivers/keyboard.h b/drivers/keyboard.h
index 33601ea..c13d4bb 100644
--- a/drivers/keyboard.h
+++ b/drivers/keyboard.h
@@ -1,3 +1,6 @@
 #pragma once
 
 void init_keyboard();
+
+extern unsigned kbd_buf_size;
+extern char *kbd_buf;
diff --git a/fs/fs.c b/fs/fs.c
index 6a5c74a..abd1fef 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -29,11 +29,15 @@ int read_file(const char* name, void* buf, uint32_t bufsize) {
         return -1;
     }
     uint32_t sector = fs_start + statbuf.reserved[0];
-    while (bufsize >= sector_size) {
+    uint32_t bytes_read = 0;
+    uint32_t file_sectors = (statbuf.size + sector_size - 1) / sector_size;
+    while (bufsize >= sector_size && file_sectors > 0) {
         read_sectors_ATA_PIO(buf, sector, 1);
         sector++;
+        file_sectors--;
         bufsize -= sector_size;
         buf += sector_size;
+        bytes_read += sector_size;
     }
-    return 0;
+    return bytes_read < statbuf.size ? bytes_read : statbuf.size;
 }
diff --git a/kernel.c b/kernel.c
index a7b3ec2..436dce6 100644
--- a/kernel.c
+++ b/kernel.c
@@ -9,6 +9,7 @@ asm(".asciz \"kernel start\"");
 #include "drivers/misc.h"
 #include "drivers/uart.h"
 #include "fs/fs.h"
+#include "string.h"
 
 void _start() {
     load_gdt();
@@ -16,19 +17,28 @@ void _start() {
     uartinit();
     load_idt();
     sti();
-    char buf[4096 + 512];
+
+    char *buf = (char*)(16 << 20);
 
     vga_clear_screen();
     printk("YABLOKO\n");
 
-    if (read_file("kernel.bin", buf, sizeof(buf)) == 0) {
+    if (read_file("kernel.bin", buf, 4096 + sector_size) > 0) {
         printk(buf + 4096);
     } else {
         printk("failed to read file\n");
     }
+    printk("\n> ");
 
     while (1) {
+        if (kbd_buf_size > 0 && kbd_buf[kbd_buf_size-1] == '\n') {
+            if (!strncmp("halt\n", kbd_buf, kbd_buf_size)) {
+                qemu_shutdown();
+            } else {
+                printk("unknown command, try: halt\n> ");
+            }
+            kbd_buf_size = 0;
+        }
         asm("hlt");
     }
-    qemu_shutdown();
 }