;        SPDX-License-Identifier: MPL-2.0
	;        SPDX-FileCopyrightText: (c) 2025 A.M. Rowsell
	;        ============================================================
	;        ZONE OS main section
	;        ============================================================
	.section "zone", "acrx"
	.global  os_print_vec
	.global  os_getch_vec
	.global  os_outbyte_vec
	.global  os_inbyte_vec
	.global  os_main_loop
	.local   os_print_signon

	.set UARTSTATUS, 6
	.set UARTDATA, 7

os_print_vec:
	;    this takes a character in a and sends it to the UART
	push af
	push bc
	push de
	ld   d, a
	ld   c, UARTSTATUS

$1:
	in  a, (c); get status byte
	bit 0, a; test bit 0
	jr  z, $1; jump back if UART not ready
	ld  a, d
	ld  c, UARTDATA
	out (c), a; send byte to uart
	pop de
	pop bc
	pop af
	ret

os_getch_vec:
	;    this gets a character from the UART and puts in in a
	push bc
	ld   c, UARTSTATUS

a2:
	in  a, (c); get status byte
	bit 1, a
	jr  z, a2
	ld  c, UARTDATA
	in  a, (c)
	pop bc
	ret

os_outbyte_vec:
	;    this takes a byte in a and sends it to port in hl
	push af
	push bc
	push hl
	ld   c, l
	out  (c), a
	pop  hl
	pop  bc
	pop  af
	ret

os_inbyte_vec:
	;    this gets a byte from port in hl and returns it in a
	push bc
	push hl
	ld   c, l
	in   a, (c)
	pop  hl
	pop  bc
	ret

os_main_loop:
	call os_print_signon

os_busy_loop:
	jp os_busy_loop

	; ======================
	; non-vectored functions
	; ======================

os_print_signon:
	ld hl, zoneSignon
	ld a, (hl)

$2:
	call os_print_vec
	inc  hl
	ld   a, (hl)
	jr   nz, $2

$3:
	ld hl, zoneCopyright
	ld a, (hl)

$4:
	call os_print_vec
	inc  hl
	ld   a, (hl)
	jr   nz, $4
	ret

zoneSignon:
	.byte "ZONE OS ver. 0.01"
	.byte 10, 13, 0

zoneCopyright:
	.byte "(c) A.M. Rowsell, license MPLv2"
	.byte 10, 13, 0

zonePrompt:
	.string "z] "

	; error messages

errorSyntax:
	.string "Syntax error!"

errorTimeout:
	.string "Command timed out."

errorNotFound:
	.string "Command/file not found."

errorHardware:
	.string "Hardware error!"

errorRAMFailed:
	.string "RAM test failed!"

stringTable:
	.word zoneSignon, zoneCopyright, zonePrompt
	.word errorSyntax, errorTimeout, errorNotFound
	.word errorHardware, errorRAMFailed