On Mon, 8 Jun 2020, Christo Crause via fpc-devel wrote:
Michael, it is entirely possible that I am misunderstanding your
suggestion, I probably don't grasp the complexities of the RTL texmode IO
system and also not explaining my intention clearly, for this I apologise.
Take for example the esp32 unit provided by Florian, here the link between
the underlying OS output and the RTL is configured by calling OpenIO and
providing readchar and writechar functions which in turn calls getchar and
putchar (
https://github.com/ccrause/freepascal/blob/76911c528251b48e18c348de1758c098ee9fb763/rtl/freertos/xtensa/esp32.pp#L106).
In this unit Florian uses a custom printpchar procedure which pushes
characters to the OS and at the end directly calls the OS fflush function.
This ensures that the haltproc message gets transmitted before the cpu goes
to sleep.
I'm trying to change the controller unit to use standard RTL write
functionality, since this gets configured during unit initialization
anyway. My attempt at "Pascalizing" Florian's version (
https://github.com/ccrause/freepascal/blob/76911c528251b48e18c348de1758c098ee9fb763/rtl/freertos/xtensa/esp8266.pp#L59)
calls the normal write functionality and works, except for the last string
before esp_deep_sleep which doesn't reach the remote terminal. At the
moment I fix this by directly calling the OS fflush function.
The only configuration option exposed via consoleio is OpenIO, which
doesn't have a parameter for a low level flush function. I could create an
overloaded OpenIO function with an extra parameter for a flush function
pointer, and call this, if assigned, at the end of Console_Write. Is this
kind of the lower level detail behind your suggestion Michael?
I would add a flushfunc to TUserData and to the OpenIO call in consoleIO:
Type
TFlushIOFunc = function(UserData: pointer): boolean;
and change
PUserData = ^TUserData;
TUserData = record
WriteChar: TWriteCharFunc;
ReadChar: TReadCharFunc;
FlushFunc : TFlushIOFunc;
UserData: Pointer;
end;
change
procedure OpenIO(var f: Text; AWrite: TWriteCharFunc; ARead: TReadCharFunc;
AMode: word; AUserData: pointer);
to
procedure OpenIO(var f: Text; AWrite: TWriteCharFunc; ARead: TReadCharFunc;
aFlush : TFlushIOFunc; AMode: word; AUserData: pointer);
and add
userdata^.FlushFunc := AFlush;
At the end of Console_Write I would call this new flush function:
if i<>t.BufPos then
InOutRes:=101
else
begin
if userdata^.FlushFunc(userdata^.UserData) then
InOutRes:=0
else
InOutRes:=101;
end;
t.BufPos:=0;
end;
Console_Write is only called when the internal buffer is full or when the
output must be forced to terminal, so that should be sufficient.
Hope this helps,
Michael.
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