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189 lines
3.5 KiB
ArmAsm
189 lines
3.5 KiB
ArmAsm
;;;
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;;;
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;;; rs232-asm.S
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;;;
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;;; PC-6001 Architecture depend RS-232C implementation,
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;;; uses a bunch of BIOS functions.
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;;;
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;;; @author Takahide Matsutsuka <markn@markn.org>
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;;;
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;;; $Id: rs232-asm.S,v 1.3 2007/11/28 09:39:30 matsutsuka Exp $
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;;;
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;; definitions of PC-6001 BIOS routines
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_rs232c_initialize = 0x19bf
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_buffer_out = 0x2627
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_char_input_sub = 0x2642
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_count_buffer = 0x26a2
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_rs232c_intr_vector = 0xfa04
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_subcpu_handshake_out = 0x0e8f
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LOG = 0
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CTK = 0
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;; export symbols
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.globl _rs232_arch_writeb
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.globl _rs232_arch_poll
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.globl _rs232_arch_init
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.area _CODE
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.if LOG
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_hex:
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.ascii "0123456789ABCDEF"
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.if CTK
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.globl _cputc_arch_asm
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.else
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.globl _libputc_asm
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.globl _screen_offset
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.endif
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_rs232_arch_putc: ; a = data
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ld hl, #0
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ld (#_screen_offset), hl
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push af
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srl a
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srl a
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srl a
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srl a
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call _rs232_arch_putc_next1
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pop af
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and a, #0x0f
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_rs232_arch_putc_next1:
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ld hl, #_hex
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_rs232_arch_putc_loop:
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or a
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jr z, _rs232_arch_putc_next2
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inc hl
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dec a
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jr _rs232_arch_putc_loop
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_rs232_arch_putc_next2:
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ld a, (hl)
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.if CTK
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call _cputc_arch_asm
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.else
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call _libputc_asm
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.endif
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ret
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.endif
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;; ---------------------------------
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;; void rs232_writeb(u8_t c)
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;; Stack; retl reth c
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;; AF__D_HL____
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;; return void
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;; ---------------------------------
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_rs232_arch_writeb:
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ld hl, #2
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add hl, sp
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ld d, (hl)
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.if LOG
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push de
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ld a, #0x77 ; 'w'
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.if CTK
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call _cputc_arch_asm
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.else
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call _libputc_asm
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.endif
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pop de
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;; ld a, d
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;; push de
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;; call _rs232_arch_putc
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;; pop de
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.endif
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_rs232_arch_writeb_loop:
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in a, (#0x81)
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and a, #0x01
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cp #0x01 ; TxRDY? 0x01/0x81/0x85
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jr nz, _rs232_arch_writeb_loop
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ld a, d
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out (#0x80), a
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ret
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;; RS-232C interrupt routine
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;; receive a byte and put it into the buffer
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_rs232_arch_intr:
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push bc
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push af
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push de
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push hl
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in a, (#0x81)
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and a, #0x02 ; RxRDY?
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jr z, _rs232_arch_intr_next ; no input
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in a, (#0x80)
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ld e, a
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ld a, #0x01
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call _buffer_out ; buffer output A=bufno, e=data
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_rs232_arch_intr_next:
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ld a, #0x0c
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call _subcpu_handshake_out ; sub CPU handshake output A
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call _rs232_arch_bufchk
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pop hl
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pop de
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pop af
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pop bc
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ei
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ret
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_rs232_arch_bufchk:
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ld a, #0x01
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call _count_buffer ; count buffer available bytes -> A
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cp #0x02 ; A >= 2?
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ld a, #0x37 ; Rx enable
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jr nc, _rs232_arch_bufchk_next ; buffer available bytes >= 2
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ld a, #0x33 ; Rx disable
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_rs232_arch_bufchk_next:
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out (#0x81),a ; buf available=0x37, buf full=0x33
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ret
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;; ---------------------------------
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;; unsigned char rs232_arch_poll(unsigned char *stat);
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;; Stack; retl reth statl stath
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;; AFBCDEHL____
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;; return input byte (*stat == 0 if no input)
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;; ---------------------------------
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_rs232_arch_poll:
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ld hl, #2
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add hl, sp
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ld e, (hl)
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inc hl
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ld d, (hl)
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ld a, #0x01
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ld (de), a
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di
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call _char_input_sub ; read from buffer
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ei
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push af
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call _rs232_arch_bufchk ; buffer check
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pop af
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jr nz, _rs232_arch_poll_ret
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xor a ; we have no data in the buffer
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ld (de), a
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jr _rs232_arch_poll_ret2
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_rs232_arch_poll_ret:
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.if LOG
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call _libputc_asm
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;; call _rs232_arch_putc
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.endif
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_rs232_arch_poll_ret2:
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pop af
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ld l, a
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ret
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;; ---------------------------------
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;; void rs232_init(unsigned long ubr);
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;; Stack; retl reth ubr1 ubr2 ubr3 ubr4
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;; AFB_DEHL____
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;; return void
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;; ---------------------------------
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_rs232_arch_init:
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ld hl, #_rs232_arch_intr
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di
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ld (#_rs232c_intr_vector), hl
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ei
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;; S2 S1 PE P L2 L1 B2 B1
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;; 0 1 0 0 1 1 1 1
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;; 8-N-1 64x clock
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ld b, #0x4f
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call _rs232c_initialize
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ld a, #0x37
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out (#0x81), a
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ret
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