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ASYNC4U.PAS
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Pascal/Delphi Source File
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1987-11-29
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16KB
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417 lines
{----------------------------------------------------------------------}
{ ASYNC4U.PAS }
{ }
{ This is a faithful translation of the famous ASYNC.INC by Michael }
{ Quinlan into a Turbo 4.0 unit. No extra frills, no modification of }
{ types, nothing fancy. But with this code you should be able to }
{ delete your $I ASYNC.INC directive, add a USES ASYNC4U statement, }
{ and recompile your existing program. If you want to add support }
{ for more ports, other computers, or change to use the new data }
{ types, all good ideas, go right ahead. With this you don't have to. }
{ }
{ Scott Gurvey, November 29 1987 }
{----------------------------------------------------------------------}
{ }
{ ASYNC.INC }
{ }
{ Async Communication Routines }
{ by Michael Quinlan }
{ with a bug fixed by Scott Herr }
{ made PCjr-compatible by W. M. Miller }
{ Highly dependant on the IBM PC and PC DOS 2.0 }
{ }
{ based on the DUMBTERM program by CJ Dunford in the January 1984 }
{ issue of PC Tech Journal. }
{ }
{ Entry points: }
{ }
{ Async_Init }
{ Performs initialization. }
{ }
{ Async_Open(Port, Baud : Integer; }
{ Parity : Char; }
{ WordSize, StpBits : Integer) : Boolean }
{ Sets up interrupt vector, initialies the COM port for }
{ processing, sets pointers to the buffer. Returns FALSE if COM }
{ port not installed. }
{ }
{ Async_Buffer_Check(var C : Char) : Boolean }
{ If a character is available, returns TRUE and moves the }
{ character from the buffer to the parameter }
{ Otherwise, returns FALSE }
{ }
{ Async_Send(C : Char) }
{ Transmits the character. }
{ }
{ Async_Send_String(S : LStr) }
{ Calls Async_Send to send each character of S. }
{ }
{ Async_Close }
{ Turn off the COM port interrupts. }
{ **MUST** BE CALLED BEFORE EXITING YOUR PROGRAM; otherwise you }
{ will see some really strange errors and have to re-boot. }
{ }
{----------------------------------------------------------------------}
{$B-} { Short circuit boolean ON }
{$I-} { I/O hecking OFF }
{$R-} { Range checking OFF }
{$S-} { Stack checking OFF }
{$V-} { Var-str checking OFF}
UNIT ASYNC4U;
INTERFACE
USES Dos;
{ global declarations }
type
LStr = String[255]; { generic string type for parameters }
const
Async_Buffer_Max = 4095;
var
Async_OriginalVector : pointer;
Async_Buffer : Array[0..Async_Buffer_Max] of char;
Async_Open_Flag : Boolean; { true if Open but no Close }
Async_Port : Integer; { current Open port number (1 or 2) }
Async_Base : Integer; { base for current open port }
Async_Irq : Integer; { irq for current open port }
Async_Buffer_Overflow : Boolean; { True if buffer overflow has happened }
Async_Buffer_Used : Integer;
Async_MaxBufferUsed : Integer;
{ Async_Buffer is empty if Head = Tail }
Async_Buffer_Head : Integer; { Locn in Async_Buffer to put next char }
Async_Buffer_Tail : Integer; { Locn in Async_Buffer to get next char }
Async_Buffer_NewTail : Integer;
{----------------------------------------------------------------------------}
{ USER CALLABLE ROUTINES }
{----------------------------------------------------------------------------}
procedure Async_Init;
{ initialize variables }
procedure Async_Close;
{ reset the interrupt system when UART interrupts no longer needed }
function Async_Open(ComPort : Integer;
BaudRate : Integer;
Parity : Char;
WordSize : Integer;
StopBits : Integer) : Boolean;
{ open a communications port }
function Async_Buffer_Check(var C : Char) : Boolean;
{ see if a character has been received; return it if yes }
procedure Async_Send(C : Char);
{ transmit a character }
procedure Async_Send_String(S : LStr);
{ transmit a string }
{----------------------------------------------------------------------------}
IMPLEMENTATION
const
UART_THR = $00; { offset from base of UART Registers for IBM PC }
UART_RBR = $00;
UART_IER = $01;
UART_IIR = $02;
UART_LCR = $03;
UART_MCR = $04;
UART_LSR = $05;
UART_MSR = $06;
I8088_IMR = $21; { port address of the Interrupt Mask Register }
var
Async_BIOS_Port_Table : Array[1..2] of Integer absolute $40:0;
{ This table is initialized by BIOS equipment determination
code at boot time to contain the base addresses for the
installed async adapters. A value of 0 means "not in-
stalled." }
const
Async_Num_Bauds = 8;
Async_Baud_Table : array [1..Async_Num_Bauds] of record
Baud, Bits : integer
end
= ((Baud:110; Bits:$00),
(Baud:150; Bits:$20),
(Baud:300; Bits:$40),
(Baud:600; Bits:$60),
(Baud:1200; Bits:$80),
(Baud:2400; Bits:$A0),
(Baud:4800; Bits:$C0),
(Baud:9600; Bits:$E0));
PROCEDURE DisableInterrupts; inline($FA {cli} ); {MACROS}
PROCEDURE EnableInterrupts; inline($FB {sti} );
procedure BIOS_RS232_Init(ComPort, ComParm : Integer);
{ Issue Interrupt $14 to initialize the UART }
{ See the IBM PC Technical Reference Manual for the format of ComParm }
var
Regs : registers;
begin
with Regs do
begin
ax := ComParm and $00FF; { AH=0; AL=ComParm }
dx := ComPort;
Intr($14, Regs)
end
end; { BIOS_RS232_Init }
{----------------------------------------------------------------------}
{ }
{ ISR - Interrupt Service Routine }
{ }
{----------------------------------------------------------------------}
procedure Async_Isr; INTERRUPT;
{ Interrupt Service Routine }
{ Invoked when the UART has received a byte of data from the
communication line }
{ re-written 9/10/84 to be entirely in machine language; original source
left as comments }
begin
Inline(
$FB/ { STI }
{ get the incomming character }
{ Async_Buffer[Async_Buffer_Head] := Chr(Port[UART_RBR + Async_Base]); }
$8B/$16/Async_Base/ { MOV DX,Async_Base }
$EC/ { IN AL,DX }
$8B/$1E/Async_Buffer_Head/ { MOV BX,Async_Buffer_Head }
$88/$87/Async_Buffer/ { MOV Async_Buffer[BX],AL }
{ Async_Buffer_NewHead := Async_Buffer_Head + 1; }
$43/ { INC BX }
{ if Async_Buffer_NewHead > Async_Buffer_Max then
Async_Buffer_NewHead := 0; }
$81/$FB/Async_Buffer_Max/ { CMP BX,Async_Buffer_Max }
$7E/$02/ { JLE L001 }
$33/$DB/ { XOR BX,BX }
{ if Async_Buffer_NewHead = Async_Buffer_Tail then
Async_Buffer_Overflow := TRUE
else }
{L001:}
$3B/$1E/Async_Buffer_Tail/ { CMP BX,Async_Buffer_Tail }
$75/$08/ { JNE L002 }
$C6/$06/Async_Buffer_Overflow/$01/ { MOV Async_Buffer_Overflow,1 }
$90/ { NOP generated by assembler for some reason }
$EB/$16/ { JMP SHORT L003 }
{ begin
Async_Buffer_Head := Async_Buffer_NewHead;
Async_Buffer_Used := Async_Buffer_Used + 1;
if Async_Buffer_Used > Async_MaxBufferUsed then
Async_MaxBufferUsed := Async_Buffer_Used
end; }
{L002:}
$89/$1E/Async_Buffer_Head/ { MOV Async_Buffer_Head,BX }
$FF/$06/Async_Buffer_Used/ { INC Async_Buffer_Used }
$8B/$1E/Async_Buffer_Used/ { MOV BX,Async_Buffer_Used }
$3B/$1E/Async_MaxBufferUsed/ { CMP BX,Async_MaxBufferUsed }
$7E/$04/ { JLE L003 }
$89/$1E/Async_MaxBufferUsed/ { MOV Async_MaxBufferUsed,BX }
{L003:}
{ disable interrupts }
$FA/ { CLI }
{ Port[$20] := $20; } { use non-specific EOI }
$B0/$20/ { MOV AL,20h }
$E6/$20 { OUT 20h,AL }
)
end; { Async_Isr }
procedure Async_Init;
{ initialize variables }
begin
Async_Open_Flag := FALSE;
Async_Buffer_Overflow := FALSE;
Async_Buffer_Used := 0;
Async_MaxBufferUsed := 0;
end; { Async_Init }
procedure Async_Close;
{ reset the interrupt system when UART interrupts no longer needed }
var
i, m : Integer;
begin
if Async_Open_Flag then
begin
{ disable the IRQ on the 8259 }
DisableInterrupts;
i := Port[I8088_IMR]; { get the interrupt mask register }
m := 1 shl Async_Irq; { set mask to turn off interrupt }
Port[I8088_IMR] := i or m;
{ disable the 8250 data ready interrupt }
Port[UART_IER + Async_Base] := 0;
{ disable OUT2 on the 8250 }
Port[UART_MCR + Async_Base] := 0;
EnableInterrupts;
SetIntVec(Async_Irq + 8,Async_OriginalVector);
{ re-initialize our data areas so we know the port is closed }
Async_Open_Flag := FALSE
end
end; { Async_Close }
function Async_Open(ComPort : Integer;
BaudRate : Integer;
Parity : Char;
WordSize : Integer;
StopBits : Integer) : Boolean;
{ open a communications port }
var
ComParm : Integer;
i, m : Integer;
begin
if Async_Open_Flag then Async_Close;
if (ComPort = 2) and (Async_BIOS_Port_Table[2] <> 0) then
Async_Port := 2
else
Async_Port := 1; { default to COM1 }
Async_Base := Async_BIOS_Port_Table[Async_Port];
Async_Irq := Hi(Async_Base) + 1;
if (Port[UART_IIR + Async_Base] and $00F8) <> 0 then
Async_Open := FALSE
else
begin
Async_Buffer_Head := 0;
Async_Buffer_Tail := 0;
Async_Buffer_Overflow := FALSE;
{ Build the ComParm for RS232_Init }
{ See Technical Reference Manual for description }
ComParm := $0000;
{ Set up the bits for the baud rate }
i := 0;
repeat
i := i + 1
until (Async_Baud_Table[i].Baud = BaudRate) or (i = Async_Num_Bauds);
ComParm := ComParm or Async_Baud_Table[i].Bits;
if Parity in ['E', 'e'] then ComParm := ComParm or $0018
else if Parity in ['O', 'o'] then ComParm := ComParm or $0008
else ComParm := ComParm or $0000; { default to No parity }
if WordSize = 7 then ComParm := ComParm or $0002
else ComParm := ComParm or $0003; { default to 8 data bits }
if StopBits = 2 then ComParm := ComParm or $0004
else ComParm := ComParm or $0000; { default to 1 stop bit }
{ use the BIOS COM port initialization routine to save typing the code }
BIOS_RS232_Init(Async_Port - 1, ComParm);
GetIntVec(Async_Irq + 8, Async_OriginalVector);
SetIntVec(Async_Irq + 8, @Async_Isr);
{ read the RBR and reset any possible pending error conditions }
{ first turn off the Divisor Access Latch Bit to allow access to RBR, etc. }
DisableInterrupts;
Port[UART_LCR + Async_Base] := Port[UART_LCR + Async_Base] and $7F;
{ read the Line Status Register to reset any errors it indicates }
i := Port[UART_LSR + Async_Base];
{ read the Receiver Buffer Register in case it contains a character }
i := Port[UART_RBR + Async_Base];
{ enable the irq on the 8259 controller }
i := Port[I8088_IMR]; { get the interrupt mask register }
m := (1 shl Async_Irq) xor $00FF;
Port[I8088_IMR] := i and m;
{ enable the data ready interrupt on the 8250 }
Port[UART_IER + Async_Base] := $01; { enable data ready interrupt }
{ enable OUT2 on 8250 }
i := Port[UART_MCR + Async_Base];
Port[UART_MCR + Async_Base] := i or $08;
EnableInterrupts;
Async_Open_Flag := TRUE; { bug fix by Scott Herr }
Async_Open := TRUE
end
end; { Async_Open }
function Async_Buffer_Check(var C : Char) : Boolean;
{ see if a character has been received; return it if yes }
begin
if Async_Buffer_Head = Async_Buffer_Tail then
Async_Buffer_Check := FALSE
else
begin
C := Async_Buffer[Async_Buffer_Tail];
Async_Buffer_Tail := Async_Buffer_Tail + 1;
if Async_Buffer_Tail > Async_Buffer_Max then
Async_Buffer_Tail := 0;
Async_Buffer_Used := Async_Buffer_Used - 1;
Async_Buffer_Check := TRUE
end
end; { Async_Buffer_Check }
procedure Async_Send(C : Char);
{ transmit a character }
var
i, m, counter : Integer;
begin
Port[UART_MCR + Async_Base] := $0B; { turn on OUT2, DTR, and RTS }
{ wait for CTS }
counter := MaxInt;
while (counter <> 0) and ((Port[UART_MSR + Async_Base] and $10) = 0) do
counter := counter - 1;
{ wait for Transmit Hold Register Empty (THRE) }
if counter <> 0 then counter := MaxInt;
while (counter <> 0) and ((Port[UART_LSR + Async_Base] and $20) = 0) do
counter := counter - 1;
if counter <> 0 then
begin
{ send the character }
DisableInterrupts;
Port[UART_THR + Async_Base] := Ord(C);
EnableInterrupts
end
else
writeln('<<<TIMEOUT>>>');
end; { Async_Send }
procedure Async_Send_String(S : LStr);
{ transmit a string }
var
i : Integer;
begin
for i := 1 to length(S) do
Async_Send(S[i])
end; { Async_Send_String }
end. { ASYNC4U UNIT }
