PROGRAM 1

PROGRAM 1 /****************************************************************************/ /* program: myuart.c */ /* author: anthony f. ortiz */ /* class: cs3590 */ /* date: january 28, 1999 */ /* description: serial chat program */ /****************************************************************************/ #include #include #include "uart.h" void main () { int port = 1; int return_value; int key_hit; byte_t mode = BAUD9600 | PARITY_NONE | STOP1 | WORD_8BIT; char ch; clrscr (); printf ("computer 1, ready:\n\n"); /* initialize the uart. */ return_value = com_open (port, mode); do { /* receive a byte from the port. */ return_value = com_in (port, &mode); /* check for a current keystroke. */ key_hit = kbhit (); /* if there is a new value in the uart register and a key hasn't been hit, print value in uart register to the screen else if a key has been hit, read character from the keyboard and send it over the serial port. */ if (return_value >= 0 && key_hit == 0) { printf ("%c", mode); } else if (key_hit != 0) { ch = getch (); mode = ch; return_value = com_out (port, mode); } } while (ch != 27); /* close uart. */ return_value = com_close (port); } /* i didn't write uart.h or uart.c. */ /* -------------------------------------------- * * uart.h * * * * cfh 1/7/94 * * -------------------------------------------- */ /* * modes for com port initialization * mode is a bitwise or of a baud, parity, stop bit and word length */ /* baud rates */ #define BAUD110 (00<<5) #define BAUD150 (01<<5) #define BAUD300 (02<<5) #define BAUD600 (03<<5) #define BAUD1200 (04<<5) #define BAUD2400 (05<<5) #define BAUD4800 (06<<5) #define BAUD9600 (07<<5) /* parity */ #define PARITY_NONE (00<<3) #define PARITY_ODD (01<<3) #define PARITY_NONE2 (02<<3) #define PARITY_EVEN (03<<3) /* stop bit */ #define STOP0 (00<<2) #define STOP1 (01<<2) /* word length */ #define WORD_7BIT (02) #define WORD_8BIT (03) /* maximum port no. */ #define PORT_MAX 4 typedef unsigned char byte_t; /* error code */ #define ERS_OK 0 /* no error */ #define ERS_TIMEOUT 1 /* timeout in i/o */ #define ERS_PORT 2 /* invaid port */ /* * these functions return 0 if no error, -1 if error. */ int com_open (int port, byte_t mode); /* open com port. */ int com_close (int port); /* close a port. */ int com_in (int port, byte_t *c); /* get a byte. */ int com_out (int port, byte_t c); /* send a byte. */ int com_stat (int port, int *status); /* get the current status. */ /* -------------------------------------------- * * uart.c * * * * cfh 1/7/94 * * -------------------------------------------- */ #include "uart.h" #define UART_VAR_SEG 40h #define UART_RBR_OFFSET 0 #define UART_THR_OFFSET 0 #define UART_MCR_OFFSET 4 #define UART_LSR_OFFSET 5 #define UART_MSR_OFFSET 6 /* uart line commands */ #define CMD_DTR 0x1 #define CMD_RTS 0x2 #define PORT_CHECK(port) { \ if (port > 4 || port < 1) { \ ers_errno = ERS_PORT; \ return -1; \ } \ port--; /* we count from 0. */ \ } int ers_errno; int com_open (int port, byte_t mode) { byte_t cmd; int rc; PORT_CHECK(port); cmd = CMD_RTS|CMD_DTR; asm { push ds; push dx; push si; push ax; mov dx, port; mov si, dx; add si, si; mov dx, UART_VAR_SEG; mov ds, dx; mov dx, [si]; add dx, UART_MCR_OFFSET; mov al, cmd; out dx, al; pop ax; pop si; pop dx; pop ds; } ers_errno = ERS_OK; return 0; } int com_close (int port) { byte_t cmd; PORT_CHECK(port); cmd = CMD_RTS; asm { push ds; push dx; push si; push ax; mov dx, port; mov si, dx add si, si; mov dx, UART_VAR_SEG; mov ds, dx; mov dx, [si]; add dx, UART_MCR_OFFSET; mov al, cmd; out dx, al; pop ax; pop si; pop dx; pop ds; } ers_errno = ERS_OK; return 0; } int com_in (int port, byte_t *c) { int rc = -1; PORT_CHECK(port); asm { push ds; push dx; push si; push ax; mov dx, port; mov si, dx add si, si; mov dx, UART_VAR_SEG; mov ds, dx; mov dx, [si]; add dx, UART_LSR_OFFSET; in al, dx; /* get the line status. */ test al, 1; jz com_in_exit; /* no input. */ mov dx, [si]; in al, dx; mov ah, 0; mov rc, ax; } com_in_exit: asm { pop ax; pop si; pop dx; pop ds; } if (rc < 0) { ers_errno = ERS_TIMEOUT; return -1; } *c = (byte_t) rc; ers_errno = ERS_OK; return 0; } int com_out (int port, byte_t c) { int rc; PORT_CHECK(port); asm { push ds; push dx; push si; push ax; mov dx, port; mov si, dx add si, si; mov dx, UART_VAR_SEG; mov ds, dx; mov dx, [si]; add dx, UART_LSR_OFFSET; } com_out_loop: asm { in al, dx; /* get the line status. */ test al, 20h; /* is the buffer empty? */ jz com_out_loop; mov dx, [si]; mov al, c; out dx, al; pop ax; pop si; pop dx; pop ds; } ers_errno = ERS_OK; return 0; } int com_stat (int port, int *status) { int rc; PORT_CHECK(port); asm { push ds; push dx; push si; push ax; mov dx, port; mov si, dx add si, si; mov dx, UART_VAR_SEG; mov ds, dx; mov dx, [si]; add dx, UART_LSR_OFFSET; in al, dx; /* get the line status. */ mov ah, al; inc dx; in al, dx; /* get the modem status. */ mov rc, ax; pop ax; pop si; pop dx; pop ds; } *status = rc; ers_errno = ERS_OK; return 0; } /* outfile: prog1.out */ /* after typing "hi, computer 2." on computer 1, computer 2 shows. */ computer 1, ready: hi, computer 2. /* after typing "hi, computer 1. " on computer 2, computer 1 shows. */ computer 2, ready: hi, computer 1. BACK TO CS3590 PAGE.