Move out console interfacing into separate file

kernel/con86.asm

@@ -0,0 +1,56 @@
+console_hide_cursor:
+  push ax
+  push cx
+  mov ah, 1
+  mov cx, 0x1F1F
+  int 0x10
+  pop cx
+  pop ax
+  ret
+
+console_show_cursor:
+  push ax
+  push cx
+  mov ah, 1
+  mov cx, 0x001F
+  int 0x10
+  pop cx
+  pop ax
+  ret
+
+; Raw console i/o without echo
+; IN   DL  character to output or FF
+; OUT  ZF  if DL=FF: zero if character input
+;      AL  if not ZF: ascii char, otherwise corrupt
+console_io:
+  cmp dl, 0xFF
+  je .read
+  push ax
+  push bx
+  mov al, dl
+  mov ah, 0x0e
+  xor bx, bx
+  int 0x10
+  pop bx
+  pop ax
+  ret
+.read:
+  call console_show_cursor
+
+  ; if no character avail, exit with leaving
+  ; cursor displayed
+  mov ah, 1
+  int 0x16
+  jz .end
+  pushf
+
+  ; actually read character
+  xor ax, ax
+  int 0x16
+
+  call console_hide_cursor
+
+  ; restore zero flag
+  popf
+.end:
+  ret

kernel/main.asm

@@ -24,8 +24,12 @@ init:
 
   call disk_parm_init
 
-  mov dl, 0x00
+  mov dx, 0x7F
-  call disk_select
+  mov byte [0x7F], 0x7F
+  mov byte [0x80], 2
+  call read_buffer
+
+  int3
 
   cli
 .halt:
@@ -35,26 +39,24 @@ init:
 init_program:
   db "HELLO.COM", 0
 
-cpm_syscall:
+; helper function for idle loops
-  cmp cl, 0
+idle:
-  je init
+  pushf
-  cmp cl, 1
+  sti
-  je console_input
+  hlt
-  cmp cl, 2
+  popf
-  je console_output
-  cmp cl, 9
-  je print_string
-  cmp cl, 10
-  je read_buffer
-  stc
   ret
 
-%include "char.asm"
+%include "syscall.asm"
+
+%include "con86.asm"
 
 %include "exec.asm"
 %include "fdc.asm"
 %include "fcb.asm"
 %include "fcbparse.asm"
+
 %include "disk.asm"
+
 %include "log2.asm"
 %include "dump.asm"

kernel/syscall.asm

@@ -1,24 +1,41 @@
+cpm_syscall:
+  cmp cl, 0
+  je init
+
+  cmp cl, 1
+  jne console_input.chain
+
+console_input.loop:
+  call idle
 console_input:
-  xor ax, ax
+  push dx
-  int 0x16
+  mov dl, 0xFF
-  ; loop until we got >0
+  call console_io
+  pop dx
+  jz console_input.loop
   test al, al
-  jz console_input
+  jz console_input.loop
-  push ax
+  push dx
-  push bx
+  mov dl, al
-  jmp console_output.shortcut
+  call console_output
-console_output:
+  pop dx
-  push ax
-  push bx
-  mov al, dl
-.shortcut:
-  mov ah, 0x0e
-  xor bx, bx
-  int 0x10
-  pop bx
-  pop ax
   ret
 
+.chain:
+  cmp cl, 2
+  jne console_output.chain
+
+console_output:
+  cmp dl, 0xFF
+  je .end
+  call console_io
+.end:
+  ret
+
+.chain:
+  cmp cl, 9
+  jne print_string.chain
+
 print_string:
   push si
   mov si, dx
@@ -33,7 +50,12 @@ print_string:
   pop si
   ret
 
+.chain:
+  cmp cl, 10
+  jne read_buffer.chain
+
 read_buffer:
+  push dx
   push bx
   push si
   xor bx, bx
@@ -51,8 +73,11 @@ read_buffer:
 .end:
   mov byte [si+bx+2], 0x0D
   mov [si+1], bl
+  mov dl, 0x0A
+  call console_output
   pop si
   pop bx
+  pop dx
   ret
 .bs:
   test bx, bx
@@ -63,3 +88,7 @@ read_buffer:
   call console_output
   dec bx
   jmp .loop
+
+.chain:
+  stc
+  ret