From 488b58b2d6be64403c14f7e9a9df66c900a37269 Mon Sep 17 00:00:00 2001
From: maelstrom <maelstrom@noreply.git.maelstrom.dev>
Date: Wed, 24 Jul 2024 18:41:52 +0300
Subject: [PATCH] Starting point copied from guess-os

---
 README.md      |   0
 input_util.asm |  57 +++++++++++++++++
 main.asm       |  33 ++++++++++
 main.bin       | Bin 0 -> 512 bytes
 mouse_util.asm | 163 +++++++++++++++++++++++++++++++++++++++++++++++++
 num_util.asm   |  43 +++++++++++++
 print_util.asm | 121 ++++++++++++++++++++++++++++++++++++
 run.sh         |   2 +
 8 files changed, 419 insertions(+)
 create mode 100644 README.md
 create mode 100644 input_util.asm
 create mode 100644 main.asm
 create mode 100644 main.bin
 create mode 100644 mouse_util.asm
 create mode 100644 num_util.asm
 create mode 100644 print_util.asm
 create mode 100755 run.sh

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e69de29
diff --git a/input_util.asm b/input_util.asm
new file mode 100644
index 0000000..03c0b6c
--- /dev/null
+++ b/input_util.asm
@@ -0,0 +1,57 @@
+read_line:
+    pusha
+
+    mov bx, read_buffer
+    .loop:
+        mov ah, 0x00
+        int 0x16 ; Read char
+
+        cmp al, 0x0D ; Is enter?
+        jne .enter_end
+            jmp .end
+        .enter_end:
+
+        cmp al, 0x08 ; Is backspace?
+        jne .backspace_end
+            ; Don't do anything if we're at col == 0
+            cmp bx, read_buffer
+            jle .backspace_end
+        
+            sub bx, 1
+            mov ah, 0x0
+            mov [bx], ah
+            
+            ; Erase the character on screen
+            mov ah, 0x0e
+            mov al, 0x08 ; Back one
+            int 0x10
+            mov al, 0x20 ; Erase it
+            int 0x10
+            mov al, 0x08 ; Back one more
+            int 0x10
+            
+            jmp .loop
+        .backspace_end
+
+        ; Don't add any characters if over the limit
+        cmp bx, read_buffer + 20
+        jge .loop
+
+        ; Add char to bx and incr
+        mov [bx], al
+        add bx, 1
+        
+        ; Display the character
+        mov ah, 0x0e
+        int 0x10
+
+        jmp .loop
+    .end:
+
+    mov al, 0x0
+    mov [bx], al ; Null terminater
+
+    popa
+    ret
+
+read_buffer: resb 20
diff --git a/main.asm b/main.asm
new file mode 100644
index 0000000..6ccdf92
--- /dev/null
+++ b/main.asm
@@ -0,0 +1,33 @@
+[org 0x7c00]
+
+main:
+    ; Video mode
+    mov ax, 0x13
+    int 0x10
+    
+    call mouse_initialize
+    call mouse_enable
+    
+lp:
+    cli
+    mov bx, [mouseX]
+    call print_hex
+    mov bx, [mouseY]
+    sti
+    
+    jmp lp
+
+jmp $ ; Halt
+
+; Make sure includes are done last, otherwise the first include will become main
+%include "print_util.asm"
+;%include "input_util.asm"
+;%include "num_util.asm"
+%include "mouse_util.asm"
+
+; Make sure data is *inside* the boot sector, or it will not be copied to the right place
+; in memory.
+
+
+times 510-($-$$) db 0
+dw 0xaa55
diff --git a/main.bin b/main.bin
new file mode 100644
index 0000000000000000000000000000000000000000..41d33889810600b2dcee5f6e5e363e4693eb12b3
GIT binary patch
literal 512
zcmdlX%y3rV#WIE$7a4wa%emCP@MY+hbF2OR`s3?=30>?q3?-af_|6J6A7*_0G4XK1
z4lW>P2QQESa$em1kHYV`v6)}th7DH@6AL?w0Z1EAQRj_=uX$cP`rmo@;A@T-x4<;Z
zi%UTI#o7Nr`JD_5%|8W7l)oQlXei|g-psUxZ-c>Ef#}y<!JC<ZY(pUX;^XFnjIVDb
z9%c(ZE4Y${p+s>9>!Iz;XGM!7b}&O2{Cw=Yoojcn9|8(8|9H*#GnyT!`h^GsP@DrI
zzJuY=cE+=!U<n}G@b+2JzQbT0K%vmir*Z+ofkAxoU2Z%bhc_}`dLZ#_Mpqa|mmAmj
pTitwawT!2_`CMulPjtw6)Gl_Z?G$sXjf#wpkdHmhFl0gKDgYp`lDq%_

literal 0
HcmV?d00001

diff --git a/mouse_util.asm b/mouse_util.asm
new file mode 100644
index 0000000..2b1b0bd
--- /dev/null
+++ b/mouse_util.asm
@@ -0,0 +1,163 @@
+; Adapted from https://stackoverflow.com/a/54367182
+
+HW_EQUIP_PS2     equ 4          ; PS2 mouse installed?
+MOUSE_PKT_BYTES  equ 3          ; Number of bytes in mouse packet
+MOUSE_RESOLUTION equ 3          ; Mouse resolution 8 counts/mm
+
+VIDEO_MODE       equ 0x13
+
+; Function: mouse_initialize
+;           Initialize the mouse if present
+;
+; Inputs:   None
+; Returns:  CF = 1 if error, CF=0 success
+; Clobbers: AX
+
+mouse_initialize:
+    push es
+    push bx
+
+    int 0x11                    ; Get equipment list
+    test ax, HW_EQUIP_PS2       ; Is a PS2 mouse installed?
+    jz .no_mouse                ;     if not print error and end
+
+    mov ax, 0xC205              ; Initialize mouse
+    mov bh, MOUSE_PKT_BYTES     ; 3 byte packets
+    int 0x15                    ; Call BIOS to initialize
+    jc .no_mouse                ;    If not successful assume no mouse
+
+    mov ax, 0xC203              ; Set resolution
+    mov bh, MOUSE_RESOLUTION    ; 8 counts / mm
+    int 0x15                    ; Call BIOS to set resolution
+    jc .no_mouse                ;    If not successful assume no mouse
+
+    push cs
+    pop es                      ; ES = segment where code and mouse handler reside
+
+    mov bx, mouse_callback_dummy
+    mov ax, 0xC207              ; Install a default null handler (ES:BX)
+    int 0x15                    ; Call BIOS to set callback
+    jc .no_mouse                ;    If not successful assume no mouse
+
+    clc                         ; CF=0 is success
+    jmp .finished
+.no_mouse:
+    stc                         ; CF=1 is error
+.finished:
+    pop bx
+    pop es
+    ret
+
+; Function: mouse_enable
+;           Enable the mouse
+;
+; Inputs:   None
+; Returns:  None
+; Clobbers: AX
+
+mouse_enable:
+    push es
+    push bx
+
+    call mouse_disable          ; Disable mouse before enabling
+
+    push cs
+    pop es
+    mov bx, mouse_callback
+    mov ax, 0xC207              ; Set mouse callback function (ES:BX)
+    int 0x15                    ; Call BIOS to set callback
+
+    mov ax, 0xC200              ; Enable/Disable mouse
+    mov bh, 1                   ; BH = Enable = 1
+    int 0x15                    ; Call BIOS to disable mouse
+
+    pop bx
+    pop es
+    ret
+
+; Function: mouse_disable
+;           Disable the mouse
+;
+; Inputs:   None
+; Returns:  None
+; Clobbers: AX
+
+mouse_disable:
+    push es
+    push bx
+
+    mov ax, 0xC200              ; Enable/Disable mouse
+    xor bx, bx                  ; BH = Disable = 0
+    int 0x15                    ; Call BIOS to disable mouse
+
+    mov es, bx
+    mov ax, 0xC207              ; Clear callback function (ES:BX=0:0)
+    int 0x15                    ; Call BIOS to set callback
+
+    pop bx
+    pop es
+    ret
+
+; Function: mouse_callback (FAR)
+;           called by the interrupt handler to process a mouse data packet
+;           All registers that are modified must be saved and restored
+;           Since we are polling manually this handler does nothing
+;
+; Inputs:   SP+4  = Unused (0)
+;           SP+6  = MovementY
+;           SP+8  = MovementX
+;           SP+10 = Mouse Status
+;
+; Returns:  None
+; Clobbers: None
+
+ARG_OFFSETS      equ 6          ; Offset of args from BP
+
+mouse_callback:
+    push bp                     ; Function prologue
+    mov bp, sp
+    push ds                     ; Save registers we modify
+    push ax
+    push bx
+    push cx
+    push dx
+
+    push cs
+    pop ds                      ; DS = CS, CS = where our variables are stored
+
+    mov al,[bp+ARG_OFFSETS+6]
+    mov bl, al                  ; BX = copy of status byte
+    mov cl, 3                   ; Shift signY (bit 5) left 3 bits
+    shl al, cl                  ; CF = signY
+                                ; Sign bit of AL = SignX
+    sbb dh, dh                  ; CH = SignY value set in all bits
+    cbw                         ; AH = SignX value set in all bits
+    mov dl, [bp+ARG_OFFSETS+2]  ; CX = movementY
+    mov al, [bp+ARG_OFFSETS+4]  ; AX = movementX
+
+    ; new mouse X_coord = X_Coord + movementX
+    ; new mouse Y_coord = Y_Coord + (-movementY)
+    neg dx
+    mov cx, [mouseY]
+    add dx, cx                  ; DX = new mouse Y_coord
+    mov cx, [mouseX]
+    add ax, cx                  ; AX = new mouse X_coord
+
+    ; Status
+    mov [curStatus], bl         ; Update the current status with the new bits
+    mov [mouseX], ax            ; Update current virtual mouseX coord
+    mov [mouseY], dx            ; Update current virtual mouseY coord
+
+    pop dx                      ; Restore all modified registers
+    pop cx
+    pop bx
+    pop ax
+    pop ds
+    pop bp                      ; Function epilogue
+
+mouse_callback_dummy:
+    retf                        ; This routine was reached via FAR CALL. Need a FAR RET
+
+mouseX:       dw 0              ; Current mouse X coordinate
+mouseY:       dw 0              ; Current mouse Y coordinate
+curStatus:    db 0              ; Current mouse status
diff --git a/num_util.asm b/num_util.asm
new file mode 100644
index 0000000..2c8c7d3
--- /dev/null
+++ b/num_util.asm
@@ -0,0 +1,43 @@
+; Loops over every character.
+; Multiplies current by 10
+; Adds [bx] - 0x30
+; add bx, 1
+parse_int:
+    pusha
+
+    ; Contains the actual result
+    mov ax, 0
+    
+    .loop:
+        mov cl, [bx]
+        
+        cmp cl, 0x0 ; End on null
+        je .end
+        
+        ; If the character is invalid, stop here.
+        cmp cl, 0x30
+        jl .end
+        cmp cl, 0x39
+        jg .end
+        
+        ; Multiply by 10
+        mov cx, 10 ; NOT 0x10
+        mul cx
+        ; Note: Has to be cx and not cl, otherwise it will be limited to 8-bits only
+        
+        mov cl, [bx]
+        sub cl, 0x30
+        mov ch, 0x0
+        add ax, cx ; Use 16-bit addition
+        
+        add bx, 1 ; Next char
+         
+        jmp .loop
+    .end:
+    
+    mov [result], ax
+    
+    popa
+    ret
+
+result: dw 0
\ No newline at end of file
diff --git a/print_util.asm b/print_util.asm
new file mode 100644
index 0000000..5ca91f8
--- /dev/null
+++ b/print_util.asm
@@ -0,0 +1,121 @@
+print:
+    pusha
+    
+    .loop:
+        mov al, [bx]
+        cmp al, 0
+        je .end ; go to end if char == 0
+        
+        mov ah, 0x0e
+        int 0x10
+        
+        add bx, 1
+        jmp .loop ; loop
+    .end:
+    
+    popa
+    ret
+    
+    
+print_nl:
+    pusha
+    
+    mov ax, 0x0e0a
+    int 0x10
+    mov ax, 0x0e0d
+    int 0x10
+    
+    popa
+    ret
+    
+println:
+    pusha
+    
+    call print
+    
+    mov ax, 0x0e0a
+    int 0x10
+    mov ax, 0x0e0d
+    int 0x10
+    
+    popa
+    ret
+
+print_hex_digit:
+    pusha
+    
+    mov al, bl
+    mov bl, 0x0F
+    and al, bl ; Get rid of all but the last nibble
+    
+    ; If the value is >= 0xA, then we need to add to the alphabetical block of the ascii table
+    cmp al, 0x0A
+    jl .skip_alpha  ; If the number is not at least 0xA, then skip this step
+    add al, 0x07 ; 'A' == 0x41, '0' == 0x30, 0x41 - 0x30 == 0x11
+    ;      Ignore     ^^^^^^^    THIS      ^^^^^^ actually.
+    ; It works and i've not got a clue why. Oh well. Such is life.
+    
+    .skip_alpha:
+    add al, 0x30 ; Add ASCII '0'
+    
+    mov ah, 0x0e
+    int 0x10
+    
+    popa
+    ret
+
+print_hex:
+    pusha
+    
+    mov ax, bx
+    
+    shr bx, 12
+    call print_hex_digit
+    
+    mov bx, ax
+    shr bx, 8
+    call print_hex_digit
+    
+    mov bx, ax
+    shr bx, 4
+    call print_hex_digit
+    
+    mov bx, ax
+    call print_hex_digit
+    
+    popa
+    ret
+    
+print_bin:
+    pusha
+    
+    mov cx, 0
+    .loop:
+        cmp cx, 16
+        je .end
+        
+        test bx, 0x8000
+        jnz .one
+            push bx
+            mov bl, 0x02
+            mov ah, 0x0e
+            mov al, 0x30
+            int 0x10
+            pop bx
+        jmp .continue
+        .one:
+            push bx
+            mov bl, 0x03
+            mov ah, 0x0e
+            mov al, 0x31
+            int 0x10
+            pop bx
+        .continue:
+        
+        shl bx, 1
+        add cx, 1
+        jmp .loop
+    .end:
+    
+    popa
+    ret
\ No newline at end of file
diff --git a/run.sh b/run.sh
new file mode 100755
index 0000000..3a62e0b
--- /dev/null
+++ b/run.sh
@@ -0,0 +1,2 @@
+nasm -f bin main.asm -o main.bin
+qemu-system-x86_64 main.bin
\ No newline at end of file