Bernd Mueller schrieb:
Holger Bruns wrote:
Holger Bruns schrieb:
I try to implement a direct port access. If this also leads to
access errors, I should give it up. Embarassing.
Accessing ports is limited to ports < 03ffh, more ports cannot be
released with fpioperm. This means to me, successful serial port
access on higher addresses cannot yet be implemented with fpc. If
this policy can be ruled out, let me know.
so you must use a very special serial hardware which is located on io
address higher than $3ff. Seems unlikely to me. In your former post,
you tried to access io address 1000 (decimal) this is $3e8
(hexadecimal) and should be an ordinary COM3. May be you are mixing up
decimal vs. hexadecimal notation.
No, the "1000" means the size of a buffer, not a part address. The port
address I try to use is 0xEC00, which is the base address for an UART on
a PCI card. Linux sees this UART as /dev/ttyS2. Accessing the registers
direcly should be easy, because 3 lines of assembler code should do this
job:
function readport (portaddress: word): byte;
begin
asm
mov %dx, portaddress
inb %al,%dx
mov readport, %al
end
end;
As long as the pascal syntax and the assembler syntax (instruction
destination source) are both correct for fpc, this function should
return the value of the selected port. This is all, what I try to do.
Best regards, Holger
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