Continued development on int 21h interface

boot/kernel.asm

@@ -35,8 +35,9 @@ init:		cli
 		mov word [0x21*4+2], cs
 		mov word [curpsp], 0x1000
 
-		mov ah, 2
 		mov dl, 0x37
+		mov ah, 2
+		int 0x21
 		int 0x21
 
 restart:

kernel/bdos.asm

@@ -10,14 +10,17 @@ absolute 0
 	resb 1
 	resb 5 ; CP/M entry point
 
-	; SS:SP, DS:DX, ES:BX and AX from the program
+	; saved userdata
 PSPAX:	resw 1
-PSPSS:	resw 1
+	; SS:SP
 PSPSP:	resw 1
-PSPDS:  resw 1
+PSPSS:	resw 1
+	; DS:DX
 PSPDX:  resw 1
+PSPDS:	resw 1
+	; ES:BX
+PSPBX:	resw 1
 PSPES:	resw 1
-PSPBX:	resd 1
 
 
 section .text
@@ -49,9 +52,25 @@ int21:	push ds
 	call .etbl
 	; syscall table
 	; cells: ptr to handler, ptr to sysret
+	; 0-7
 	dw restart, sret
 	dw getc, sretb
 	dw putc, sret
+	dw err, sret ; reader input
+	dw err, sret ; punch outout
+	dw err, sret ; list output
+	dw conio, sret ; direct console i/o
+	dw err, sret
+	; 8-f
+	dw err, sret
+	dw err, sret ; print string
+	dw err, sret ; read into buffer
+	dw err, sret ; console status
+	dw err, sret ; return version num
+	dw err, sret ; reset disks
+	dw err, sret ; select disk
+	dw err, sret ; open file
+
 	; set up a return chain and execute it
 	; first return into handler function
 	; second return into appropiate sysret
@@ -61,26 +80,27 @@ int21:	push ds
 	push word [cs:bx]
 	ret
 
+err:	mov ah, 0xFF
+	ret
+
 	; sysret handlers
 	; return ES:BX to user
-sretd:	call pspds
+sretd:	mov ds, [ss:curpsp]
 	jmp sret.l02
 
 	; return BX to user
-sretw:	call pspds
+sretw:	mov ds, [ss:curpsp]
 	mov es, [PSPES]
 	jmp sret.l02
 
 	; return AL to user
-sretb:	push ax
-	call pspds
-	pop ax
+sretb:	mov ds, [ss:curpsp]
 	mov ah, [PSPAX+1]
 	les bx, [PSPBX]
 	jmp sret.l03
 
 	; return without result
-sret:	call pspds
+sret:	mov ds, [ss:curpsp]
 .l01:	les bx, [PSPBX]
 .l02:	mov ax, [PSPAX]
 .l03:	mov ss, [PSPSS]

kernel/char.asm

@@ -1,11 +1,30 @@
-getc:	xor ax, ax
-	int 0x16
+section .text
+
+getc:	call conin
 	test al, al
 	jz getc
 	ret
 
-putc:	mov al, dl
+putc:	; flag checking here
+conout:	mov al, dl
 	mov ah, 0x0e
 	xor bx, bx
 	int 0x10
 	ret
+
+conio:	cmp dl, 0xFF
+	jne conout
+conin:	call const
+	test al, al
+	jz .ret
+	mov al, 0
+	int 0x16
+.ret:	ret
+
+const:	mov ah, 1
+	int 0x16
+	jz .emp
+.rdy:	mov ax, 0xFF
+	ret
+.emp:	mov al, 0
+	ret