simple serial port monitor

[redskull]

I've been fooling around with serial ports for the last week or so, and i thought I would share what I came up with.  This program just monitors a serial port for any incoming data, and displays it in a console window.  All the settings are hard coded, so it has to get reassembled for your particular purpose.  It *seems* to work, but i have limited ability to fully test it.  As always, suggestions, comments, bug reports, flames, and caustic insults are highly encouraged.  Thanks again to everyone for helping to edu-ma-cate me.
alan

Code Select Expand

.486
.model flat, stdcall
option casemap:none

include \masm32\include\windows.inc
include \masm32\include\kernel32.inc
includelib \masm32\lib\kernel32.lib
include \masm32\include\user32.inc
includelib \masm32\lib\user32.lib

.data
szFrameError db "!"                            ; Display character for errors
displaystring1 db "Monitoring for Data:",0     ; Output display string

.data?
hSerialPort DWORD ?                             ; handle for serial port
SerialSettings DCB {?}                          ; settings for serial port
SerialTimeOuts COMMTIMEOUTS {?}                 ; timeout settings for serial port
NumberOfBytesRead DWORD ?                       ; rcv variable for bytes read from ReadFile
EvtMask DWORD ?                                 ; rcv variable for comm event returned
SerialError DWORD ?                             ; holder for error occured
RcvBuffer DWORD ?                               ; variable for holding input to go to screen

hConsoleOutput DWORD ?                          ; Handle to the display console
ConsoleWriteBytes DWORD ?                       ; rcv variable for bytes written to console

.const
Comm1 db "COM1:", 0                             ; Comm port constants
Comm2 db "COM2:", 0
Comm3 db "COM3:", 0

.code
start:
;-----------------------------
; Allocate a console for displaying output
;-----------------------------
invoke AllocConsole
invoke GetStdHandle, STD_OUTPUT_HANDLE
mov hConsoleOutput, eax
; do not process control codes, display thier hex equivalents
invoke SetConsoleMode, hConsoleOutput, ENABLE_WRAP_AT_EOL_OUTPUT

;-----------------------------
; Serial Port initialization
;-----------------------------
invoke CreateFile, ADDR Comm1, GENERIC_READ OR\         ; Open the Serial Port
    GENERIC_WRITE,0, NULL, OPEN_EXISTING,0,NULL
mov hSerialPort, eax                                    ; save the handle
mov SerialSettings.DCBlength, SIZEOF DCB                ; configure the Settings variable
invoke GetCommState, hSerialPort, ADDR SerialSettings   ; fill it with the current settings
mov SerialSettings.BaudRate, CBR_19200                  ; Baud Rate
mov SerialSettings.ByteSize, 8                          ; Data Bits: 8
mov SerialSettings.Parity, NOPARITY                     ; Parity: None
mov SerialSettings.StopBits, ONESTOPBIT                 ; Stop Bits: 1
mov SerialSettings.fOutxCtsFlow, FALSE                  ; No RTS
mov SerialSettings.fRtsControl, RTS_CONTROL_DISABLE     ; No CTS
mov SerialSettings.fOutxDsrFlow, FALSE                  ; No DSR TX inhibiting
mov SerialSettings.fDsrSensitivity, FALSE               ; No DSR RX inhibiting
mov SerialSettings.fDtrControl, DTR_CONTROL_ENABLE      ; Enable DTR Signal
mov SerialSettings.fOutX, TRUE                          ; xOn/xOff enabled for TX
mov SerialSettings.fInX, FALSE                          ; Suspend Xon/Xoff for RCV
mov SerialSettings.fNull, TRUE                          ; Discard NULL bytes
mov SerialSettings.fAbortOnError, FALSE                 ; Do not Abort on Error
mov SerialSettings.fBinary, TRUE                        ; Binary Transfer
mov SerialSettings.fParity, TRUE                        ; Parity Enabled
invoke SetCommState, hSerialPort, ADDR SerialSettings   ; Apply the new settinsg

; Set the Time-outs to occur immedietly with everything in the buffer
invoke GetCommTimeouts, hSerialPort, ADDR SerialTimeOuts
mov SerialTimeOuts.ReadIntervalTimeout, MAXDWORD
mov SerialTimeOuts.ReadTotalTimeoutMultiplier, 0
mov SerialTimeOuts.ReadTotalTimeoutConstant, 0
mov SerialTimeOuts.WriteTotalTimeoutMultiplier, 0
mov SerialTimeOuts.WriteTotalTimeoutConstant, 0
invoke SetCommTimeouts, hSerialPort, ADDR SerialTimeOuts

;Generate events for received bytes and errors
invoke SetCommMask, hSerialPort, (EV_RXCHAR OR EV_ERR)
;------------------------------------------------------

invoke WriteConsole, hConsoleOutput, ADDR displaystring1, \  ; display a prompt
    SIZEOF displaystring1, ADDR NumberOfBytesRead, NULL
   
;-----------------------------
; Poll the serial port for RCV data
;-----------------------------

.WHILE TRUE                                                 ; Enter an endless loop
invoke WaitCommEvent, hSerialPort, ADDR EvtMask, NULL      ; Hold up for either a character or an error

.IF EvtMask == EV_ERR                                      ; If an error came in...
  invoke SetConsoleTextAttribute, hConsoleOutput,\          ; change to a red font
   FOREGROUND_RED
  invoke WriteConsole, hConsoleOutput, ADDR szFrameError,\  ; print an exclamation point
   SIZEOF szFrameError, ADDR ConsoleWriteBytes, NULL
  invoke SetConsoleTextAttribute, hConsoleOutput,\          ; change back to white font
   FOREGROUND_BLUE OR FOREGROUND_GREEN OR FOREGROUND_RED
  invoke ClearCommError, hSerialPort, ADDR SerialError, NULL; clear the error
.ENDIF

.IF EvtMask == EV_RXCHAR                                   ; if a chracter was recieved...
  .WHILE TRUE                                               ; start a loop to empty out the serial port
   invoke ReadFile, hSerialPort, RcvBuffer, SIZEOF\         ; Read in one DWORD from the serial port
    RcvBuffer, ADDR NumberOfBytesRead, NULL
   .BREAK .IF NumberOfBytesRead == 0                        ; exit if the buffer is empty
   invoke WriteConsole, hConsoleOutput, RcvBuffer,\         ; print out any characters recieved
    NumberOfBytesRead, ADDR ConsoleWriteBytes, NULL
  .ENDW
.ENDIF
.ENDW

invoke CloseHandle, hSerialPort                             ; close the serial port
invoke ExitProcess, NULL                                     ; End the Program

END start

[six_L]

Code Select Expand

DCB STRUCT                         
DCBlength     DWORD ?   
BaudRate      DWORD ?   
fbits         BITRECORD <> 
wReserved     WORD ?   
XonLim        WORD ?   
XoffLim       WORD ?   
ByteSize      BYTE ?   
Parity        BYTE ?   
StopBits      BYTE ?   
XonChar       BYTE ?   
XoffChar      BYTE ?   
ErrorChar     BYTE ?   
EofChar       BYTE ?   
EvtChar       BYTE ?   
wReserved1    WORD ?   
DCB ENDS