Category : Assembly Language Source Code
Archive   : CAS8051.ZIP
Filename : CRC.ASM

include "8052.h"

;;; Process stack
HW equ 73h ;;; int **HW;
Stack equ 74h ;;; int *Stack[8];

;;; /* Interrupt descriptor table. */
SP_RI equ 7ch
SP_TI equ 7dh
SP_BASE equ 7eh

org 00h
sjmp Start

org 23h
jbc TI, DidTx
jbc RI, DidRx
reti
DidTx:
mov R0, #SP_TI
acall Resume
reti
DidRx:
mov R0, #SP_RI
acall Resume
reti

Start: ;;; Install main(), set its return address to Idle().
mov HW, #Stack ;;; HW = &Stack[0];
mov SP, #(SP_BASE - 1) ;;; SP = SP_BASE - 1;
mov DPTR, #Exit
push DPL
push DPH ;;; @SP++ = Exit();
acall main
Idle:
orl PCON, #1
sjmp Idle

Pause: ;;; void Pause(int @@R0) {
mov @R0, SP ;;; @R0 = SP;
dec HW
mov R0, HW
mov SP, @R0 ;;; SP = @--HW;
ret ;;; "idle until resume";
Resume:
mov R1, HW
inc HW
mov @R1, SP ;;; @HW++ = SP;
mov SP, @R0 ;;; SP = @R0;
mov @R0, #(SP_BASE + 1) ;;; @R0 = SP_BASE + 1;
ret ;;; }

Spawn: ;;; int Spawn(int @R0, void *(DPTR())) {
mov R1, HW
inc HW
mov @R1, SP ;;; @HW++ = SP;
dec R0
mov SP, R0 ;;; SP = --R0;
acall _Enter ;;; (*DPTR)();
Exit:
dec HW
mov R0, HW
mov SP, @R0 ;;; SP = @--HW;
ret ;;; }
_Enter:
push DPL
push DPH
ret

;;; RS-485 SERIAL COMMUNICATIONS.
;;; Modes:
;;; (1) Receive data (REN = 1, T0 = 0)
;;; (a) Wait for address (SM2 = 1)
;;; (b) Wait for data (SM2 = 0)
;;; (2) Send data (REN = 0, T0 = 1)

SER_ADDR equ ':'

SetPort:
mov SCON, #11000000b ;;; Serial comm: 8 bits, no parity, 1 stop bit.
clr PS
clr RCLK
clr TCLK
mov A, TMOD
anl A, #0fh
add A, #00100000b ;;; Timer 1: baud rate timer.
mov TMOD, A
mov TH1, #-1 ;;; Baud rate: 28800 baud.
orl PCON, #80h ;;; Baud rate now 57600 baud.
setb TR1
clr TB8
clr RI
clr TI
setb ES
ret

SetRx: ;;; Set mode for "Receive data"
clr T0
setb REN
ret

SetTx: ;;; Set mode for "Send data"
clr REN
setb T0
ret

getchar:
setb SM2 ;;; Set mode for "Wait for address";
GetAddress: ;;; do {
mov R0, #SP_RI
acall Pause ;;; wait for reception;
mov A, SBUF ;;; A = received character;
xrl A, #SER_ADDR
jnz GetAddress ;;; } while (A != SER_ADDR);
clr SM2 ;;; Set mode for "Wait for data";
mov R0, #SP_RI
acall Pause ;;; wait for reception;
mov A, SBUF ;;; return received character;
ret

nl:
mov A, #13
acall putchar
mov A, #10
putchar:
mov SBUF, A
mov R0, #SP_TI
acall Pause
ret

;;; APPLICATION
putnib:
anl A, #0fh
cjne A, #10, $ + 3
jc isdigit
add A, #('a' - 10)
acall putchar
ret
isdigit:
add A, #'0'
acall putchar
ret

puthex:
push ACC
push DPL
push DPH
mov DPTR, #Values
movc A, @A + DPTR
xrl A, R3
mov R3, A
pop DPH
pop DPL
pop ACC
push ACC
swap A
acall putnib
pop ACC
acall putnib
ret

hexs:
mov DPTR, #0000h
hexsLoop:
mov A, DPH
cjne A, #20h, $ + 3
jnc hexsBreak ;;; for (Addr = 0x0000; Addr <= 0x2000; ) {
mov A, #':'
acall putchar ;;; putchar(':');
mov R3, #0 ;;; CheckSum = 0;
mov A, #10h
acall puthex
mov A, DPH
acall puthex
mov A, DPL
acall puthex
mov A, #0
acall puthex ;;; printf("%2x%4x%2x", 0x10, Addr, 0);
mov R2, #10h
DataLoop: ;;; for (R2 = 0x10; R2 > 0; R2--) {
clr A
movc A, @A + DPTR
inc DPTR
acall puthex ;;; printf("%2x", *Addr++);
djnz R2, DataLoop ;;; }
mov A, R3
acall puthex
acall nl ;;; printf("%2x\n", CheckSum);
sjmp hexsloop ;;; }
hexsBreak:
mov A, #':'
acall putchar ;;; putchar(':');
mov R3, #0
mov A, #00h
acall puthex
mov A, DPH
acall puthex
mov A, DPL
acall puthex
mov A, #1
acall puthex ;;; printf("%2x%4x%2x", 0, Addr, 1);
mov A, R3
acall puthex
acall nl ;;; printf("%2x\n", CheckSum);
ret

Echo:
acall SetPort ;;; SetPort();
acall SetRx ;;; set for receive mode;
EchoLoop:
acall getchar ;;; while (1) switch (A = getchar()) {
X0: cjne A, #'s', X1 ;;; case 's':
acall SetTx ;;; set for transmit mode;
acall hexs ;;; hexs();
acall SetRx ;;; set for receive mode;
sjmp EchoLoop ;;; break;
X1: ;;; default:
acall SetTx ;;; set for transmit mode;
acall putchar ;;; putchar(A);
acall SetRx ;;; set for receive mode;
sjmp EchoLoop ;;; }

main:
mov R0, #90h
mov DPTR, #Echo
acall Spawn
setb EA
ret

;;; Polynomial used: x^8 + x^6 + x^5 + x^3 + x^0
Values:
db 00h, 69h,0d2h,0bbh,0cdh,0a4h, 1fh, 76h
db 0f3h, 9ah, 21h, 48h, 3eh, 57h,0ech, 85h
db 0e6h, 8fh, 34h, 5dh, 2bh, 42h,0f9h, 90h
db 15h, 7ch,0c7h,0aeh,0d8h,0b1h, 0ah, 63h
db 0a5h,0cch, 77h, 1eh, 68h, 01h,0bah,0d3h
db 56h, 3fh, 84h,0edh, 9bh,0f2h, 49h, 20h
db 43h, 2ah, 91h,0f8h, 8eh,0e7h, 5ch, 35h
db 0b0h,0d9h, 62h, 0bh, 7dh, 14h,0afh,0c6h
db 4ah, 23h, 98h,0f1h, 87h,0eeh, 55h, 3ch
db 0b9h,0d0h, 6bh, 02h, 74h, 1dh,0a6h,0cfh
db 0ach,0c5h, 7eh, 17h, 61h, 08h,0b3h,0dah
db 5fh, 36h, 8dh,0e4h, 92h,0fbh, 40h, 29h
db 0efh, 86h, 3dh, 54h, 22h, 4bh,0f0h, 99h
db 1ch, 75h,0ceh,0a7h,0d1h,0b8h, 03h, 6ah
db 09h, 60h,0dbh,0b2h,0c4h,0adh, 16h, 7fh
db 0fah, 93h, 28h, 41h, 37h, 5eh,0e5h, 8ch
db 94h,0fdh, 46h, 2fh, 59h, 30h, 8bh,0e2h
db 67h, 0eh,0b5h,0dch,0aah,0c3h, 78h, 11h
db 72h, 1bh,0a0h,0c9h,0bfh,0d6h, 6dh, 04h
db 81h,0e8h, 53h, 3ah, 4ch, 25h, 9eh,0f7h
db 31h, 58h,0e3h, 8ah,0fch, 95h, 2eh, 47h
db 0c2h,0abh, 10h, 79h, 0fh, 66h,0ddh,0b4h
db 0d7h,0beh, 05h, 6ch, 1ah, 73h,0c8h,0a1h
db 24h, 4dh,0f6h, 9fh,0e9h, 80h, 3bh, 52h
db 0deh,0b7h, 0ch, 65h, 13h, 7ah,0c1h,0a8h
db 2dh, 44h,0ffh, 96h,0e0h, 89h, 32h, 5bh
db 38h, 51h,0eah, 83h,0f5h, 9ch, 27h, 4eh
db 0cbh,0a2h, 19h, 70h, 06h, 6fh,0d4h,0bdh
db 7bh, 12h,0a9h,0c0h,0b6h,0dfh, 64h, 0dh
db 88h,0e1h, 5ah, 33h, 45h, 2ch, 97h,0feh
db 9dh,0f4h, 4fh, 26h, 50h, 39h, 82h,0ebh
db 6eh, 07h,0bch,0d5h,0a3h,0cah, 71h, 18h
end