rdos/kernel/main.asm

cpu 8086
org 0x0
jmp init

isr_dos_main:
  cmp ah, 0x01
  je isr_getc_echo
  cmp ah, 0x02
  je isr_putc
  cmp ah, 0x25
  je isr_intr_register
  jmp isr_invalid

%include "intr.asm"
%include "chario.asm"

; ISR for invalid subfunctions or unimplemented
isr_invalid:
  mov bp, 0xFEFE
  int3
.hlt:
  hlt
  jmp .hlt
; ISR tail to set carry flag to signal error
isr_error:
  push bp
  mov bp, sp
  ; set carry flag
  or WORD [SS:BP+6], 1
  pop bp
isr_return:
  iret

%include "drive.asm"

init:
  mov ax, cs
  mov ds, ax
  mov es, ax

  mov di, kernel_end
  call drive_setup

  mov dx, isr_dos_main
  mov ax, 0x2521
  pushf
  push cs
  call isr_dos_main

  mov dl, 0x37
  mov ah, 0x02
  int 0x21

  cli
.halt:
  hlt
  jmp .halt


kernel_end:
Change kernel blob format to be option rom compatible 2019-04-20 23:02:35 +02:00			`cpu 8086`
Run kernel with from offset 0 I try to get the interrupt handlers into a offset as low as possible. This is necessity if i want to relocate it later on its own. For running from HMA, a minimal offset of 16 bytes would still be necessary. 2019-09-24 00:06:25 +02:00			`org 0x0`
Rework interrupt handling, realign stuff for relative jumps 2019-09-10 23:38:52 +02:00			`jmp init`
Change kernel blob format to be option rom compatible 2019-04-20 23:02:35 +02:00
Add basic 21h functions 2019-09-06 00:24:39 +02:00			`isr_dos_main:`
Rework interrupt handling, realign stuff for relative jumps 2019-09-10 23:38:52 +02:00			`cmp ah, 0x01`
			`je isr_getc_echo`
			`cmp ah, 0x02`
			`je isr_putc`
Remove intr function not in line with int 21h If we have them, use them for setting up ourselves 2019-09-10 23:50:58 +02:00			`cmp ah, 0x25`
			`je isr_intr_register`
Rework interrupt handling, realign stuff for relative jumps 2019-09-10 23:38:52 +02:00			`jmp isr_invalid`
Work on interrupt subfunctions, remove drvtab experiments 2019-09-08 17:18:37 +02:00
Rework interrupt handling, realign stuff for relative jumps 2019-09-10 23:38:52 +02:00			`%include "intr.asm"`
Remove intr function not in line with int 21h If we have them, use them for setting up ourselves 2019-09-10 23:50:58 +02:00			`%include "chario.asm"`
Work on interrupt subfunctions, remove drvtab experiments 2019-09-08 17:18:37 +02:00
			`; ISR for invalid subfunctions or unimplemented`
			`isr_invalid:`
			`mov bp, 0xFEFE`
			`int3`
			`.hlt:`
			`hlt`
			`jmp .hlt`
			`; ISR tail to set carry flag to signal error`
Add basic 21h functions 2019-09-06 00:24:39 +02:00			`isr_error:`
			`push bp`
			`mov bp, sp`
			`; set carry flag`
			`or WORD [SS:BP+6], 1`
			`pop bp`
			`isr_return:`
			`iret`

Add attempt for drive table to kernel 2019-09-19 22:02:16 +02:00			`%include "drive.asm"`

Rework interrupt handling, realign stuff for relative jumps 2019-09-10 23:38:52 +02:00			`init:`
Remove intr function not in line with int 21h If we have them, use them for setting up ourselves 2019-09-10 23:50:58 +02:00			`mov ax, cs`
			`mov ds, ax`
			`mov es, ax`
Work on interrupt subfunctions, remove drvtab experiments 2019-09-08 17:18:37 +02:00
Add attempt for drive table to kernel 2019-09-19 22:02:16 +02:00			`mov di, kernel_end`
			`call drive_setup`

Remove intr function not in line with int 21h If we have them, use them for setting up ourselves 2019-09-10 23:50:58 +02:00			`mov dx, isr_dos_main`
			`mov ax, 0x2521`
			`pushf`
			`push cs`
			`call isr_dos_main`
Add drive table initialisation 2019-09-03 12:58:06 +02:00
Add attempt for drive table to kernel 2019-09-19 22:02:16 +02:00			`mov dl, 0x37`
			`mov ah, 0x02`
			`int 0x21`
Rework interrupt handling, realign stuff for relative jumps 2019-09-10 23:38:52 +02:00
			`cli`
			`.halt:`
			`hlt`
			`jmp .halt`
Add basic 21h functions 2019-09-06 00:24:39 +02:00
Add attempt for drive table to kernel 2019-09-19 22:02:16 +02:00
Work on interrupt subfunctions, remove drvtab experiments 2019-09-08 17:18:37 +02:00			`kernel_end:`