add hard disk operations

mbr/hd.asm

@@ -0,0 +1,100 @@
+
+;; LBA-28 mode
+
+;; set sector count of reading
+;; port: 0x1f2
+;; 8 bit mode
+;; @param: sector count, 1 byte
+;; if count=0, means 256 sectors
+;; i.e. we can access 256*512/1024=128GB
+%macro set_read_sector_count 1
+    mov dx, 0x1f2
+    mov al, %1
+    out dx, al                  ;; 0x1f2
+%endmacro
+;;=============================================================================
+
+;; start reading from the given sector
+;; NOTE: use master hard disk
+;; @param: start sector number, 4 bytes
+%macro set_LBA_sector_number 1
+    mov dx, 0x1f3
+    mov al, (%1 & 0xFF)         ;; LBA addr [7:0]
+    out dx, al                  ;; 0x1f3 (8 bit)
+    inc dx
+
+    mov al, ((%1 >> 8) & 0xFF)  ;; LBA addr [15:8]
+    out dx, al                  ;; 0x1f4 (8 bit)
+    inc dx
+
+    mov al, ((%1 >> 16) & 0xFF) ;; LBA addr [23:16]
+    out dx, al                  ;; 0x1f5 (8 bit)
+    inc dx
+
+    ;; 0x1f6 bits table
+    ;; ------------------------------------------------------
+    ;; H: | 1 | CHS(0) or LBA(1) | 1 | master(0) or slave(1)
+    ;; L:           LBA addr [27:24]
+    ;; ------------------------------------------------------
+    mov al, ((%1 >> 24) & 0xF)  ;; LBA addr [27:24]
+    or al, 0xe0                 ;; combine high & low parts
+    out dx, al                  ;; 0x1f6 (8 bit)
+%endmacro
+;;=============================================================================
+
+;; 0x1f7 OUT: read request command
+;; 8 bit mode
+%macro request_hd_read 0
+    mov dx, 0x1f7
+    mov al, 0x20                ;; read command
+    out dx, al                  ;; 0x1f7 (8 bit)
+%endmacro
+;;=============================================================================
+
+;; 0x1f7 IN: status
+;; 8 bit mode
+;; 7 - 0
+;; |BUSY|x|x|x|DRQ|x|x|ERR|
+;; BUSY: 1 - HD is busy.
+;; DRQ: 1 - HD is ready for exchanging data.
+;; ERR: 1 - Something is wrong, read port 0x1f1
+%macro wait_for_hd_ready 0
+        mov dx, 0x1f7
+    .wait:
+        in al, dx
+        and al, 0x88
+        cmp al, 0x08 ;; check whether hd is ready (BUSY=0,DRQ=1,ERR=0)
+        jnz .wait
+%endmacro
+;;=============================================================================
+
+;; read data from hd via port 0x1f0 (16 bit mode)
+;; @param: count of word, 2 bytes
+;; total size: param * 2 (bytes)
+%macro read_hd_data 1
+        mov cx, %1
+        mov dx, 0x1f0
+    .readw:
+        in ax, dx
+        mov [bx], ax    ;; save data to DS:BX
+        add bx, 2
+        loop .readw
+%endmacro
+;;=============================================================================
+
+org 0x7c00
+
+start:
+    mov ax, cs
+    mov ds, ax
+    mov es, ax
+
+    set_read_sector_count 2
+    set_LBA_sector_number 0x84211248
+
+    jmp $
+;;=============================================================================
+
+times (510 - ($-$$)) db 0
+dw 0xaa55
+;;=============================================================================

mbr/nmake.sh

@@ -5,7 +5,7 @@ then
 	mkdir -v bin
 fi
 
-nasm -f bin -o bin/$1.bin $1.asm
+nasm -f bin -o bin/$1.bin -l bin/$1.lst $1.asm
 
 dd if=bin/$1.bin of=bin/c.img seek=0 bs=512 count=1 conv=notrunc
 cd bin