;***************************************************************************
;	MODEM.INC
;
;	Donahe, Brendan D.	Parks, Jerome C.
;
;	Final Project
;	EE490 Section 4
;	Copyright (C) December 4, 1996
;***************************************************************************

ORIGINATE       equ     0
ANSWER          equ     1

SRATE           equ     9600    ; Sample rate
FREQ            equ     2400    ; frequency in Hz of transmit signal
BAUD            equ     600

INTERVAL        equ     SRATE/BAUD       ; 16 samples/symbol
;INTERVAL       equ     SRATE

SINSIZ          equ     256     ; Length of wavetable ROM (y:$0100)
MASK            equ     SINSIZ-1
FUND_PERIOD     equ     (@cvf(SINSIZ)/@cvf(SRATE))    ; 1/Fundamental_Frequency

PWR_THRESH      equ     0.01
MAG_THRESH      equ     .015    ; threshold to determine magnitude

					; ---Port-B bit position names
ACK		equ	13		; acknowledge back to host
STR		equ	12		; data strobe from host
INI		equ	11		; initialization
DSL		equ	10

;******************************* X Memory ***********************************
		org     x:$0020

int_delta       dc      0               ; sine table integer delta 

;mode		dc	ORIGINATE	; ORIGINATE or ANSWER mode
mode		dc	ANSWER

NO_HOSTPORT	equ	0		; says whether the hostport connection
HOSTPORT	equ	1		;  will be used or not
hostport_mode	dc	NO_HOSTPORT	

txrx_mode       dc      1               ; negotiation or send/receive phase:
					;  1. negotiation_tx
					;  2. negotiation_rx
					;  3. txrx

negotiation_count       dc      RECV_BUFSIZ*3   ; counter for negotiate_rx

DATA_START      equ     $400
		org     x:DATA_START
NUM_CHARS       equ     41		; number of characters
data_bytes      dsm     NUM_CHARS
		org     x:data_bytes
		dc      'A','B','C','D','E','F','G','H','I'
		dc      'J','K','L','M','N','O','P','Q','R'
		dc      'S','T','U','V','W','X','Y','Z'         ; 26 chars
		dc	$09		; tab character
		dc      'H','e','l','l','o',' ','W','o','r','l','d','!'
		dc	$0D,$0A		; carriage return, line feed
;               dc      $0f,$0f,$0f,$0f ; 110000111100
;               dc      $33,$33,$33,$33 ; 110011001100
;               dc      $55,$55,$55,$55 ; 110101010100
;               dc      $00,$00,$00,$00 ; 110000000000
;               dc      $ff,$ff,$ff,$ff ; 111111111100
;               dc      $77,$77,$77,$77 ; 110111011100
;               dc      $e8,$e8,$e8,$e8 ; 111110100000

RECV_BUFSIZ             equ     4
recv_filter             dsm     RECV_BUFSIZ
recv_correlation        dsm     RECV_BUFSIZ
temp_correlation_pwr    dc      0

;******************************* Y Memory ***********************************
		org     y:20

prev_dibit      dc      0               ; holds the previous dibit
temp_dibit      dc      0               ;  dibit: Amplitude, Phase

SHIFT_NONE      equ     0
SHIFT_180       equ     1
prev_phase      dc      SHIFT_NONE      ; hold previous transmitted phase

frame_counter   dc      INTERVAL        ; max length to stay within boundary

START_BITS      equ     1               ; Equates for mode of the frame
DATA_BITS       equ     2               ; if START_BITS, need to transmit 11b
PARITY_STOP     equ     4               ; otherwise transmit data bit or
frame_mode      dc      START_BITS      ; parity and stop bits.

data_byte       dc      0               ; what current data byte is
data_count      dc      4               ; need next byte if zero
data_dibit      dc      0               ; current dibit being transmitted

parity          dc      0               ; keeps track of parity for a byte

MAX_DIBIT_COUNTER       equ     5
dibit_counter   dc      0               ; holds the current state of the frame
filter_dibit_count      dc      0       ; for re-syncing the filter coefs

MAX_STARTBIT_COUNT      equ     4
startbit_count  dc      MAX_STARTBIT_COUNT ; padding before a sample is grabbed

interval_count  dc      0

recv_queue      dsm     RECV_BUFSIZ     ; store incoming samples

		org     y:$0200
extra_zero      dc      0

FRAME_OUT_SIZE  equ     1024
frame_out       dsm     FRAME_OUT_SIZE  ; arbitrary size to store data in