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sys/stdio_uart: add stdio_clear_stdin#19837

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HendrikVE:stdio_uart_add_flush_rx
Nov 27, 2024
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sys/stdio_uart: add stdio_clear_stdin#19837
maribu merged 1 commit intoRIOT-OS:masterfrom
HendrikVE:stdio_uart_add_flush_rx

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@HendrikVE
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@HendrikVE HendrikVE commented Jul 19, 2023

Contribution description

This PR introduces a new pseudomodule. It is currently only implemented for stdio_uart.

The use case is to clear the input buffer so we can throw away the remaining input (like \n for example) after a call of scanf for the next call of scanf.

Testing procedure

Have an application with multiple calls of scanf and use stdio_flush_rx at some places and don't use it on others.

@github-actions github-actions bot added Area: build system Area: Build system Area: sys Area: System labels Jul 19, 2023
@kaspar030
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kaspar030 commented Jul 19, 2023

bikeshedding: you'd "flush" output, "drain" input?

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HendrikVE commented Jul 19, 2023

bikeshedding: you'd "flush" output, "drain" input?

I think I'd rather go with a simple "clear" then instead, maybe "stdio_clear_input"?

@MrKevinWeiss
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MrKevinWeiss commented Oct 6, 2023

Should we get this in for the release?

@benpicco benpicco added the CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR label Nov 10, 2023
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riot-ci commented Nov 10, 2023 •
edited
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Murdock results

✔️ PASSED

6f9edfe sys/stdio_uart: add stdio_clear_stdin

Success Failures Total Runtime
10242 0 10246 15m:08s

Artifacts

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benpicco commented Apr 5, 2024

Needs a rebase, you can move this to sys/stdio/stdio.c now.

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fabian18 commented Apr 16, 2024

What about ethos? stdio.c is not being compiled when using stdio_ethos.

stdio.inc.mk

STDIO_LEGACY_MODULES = \
  ethos_stdio \
  stdio_ethos \
  stdio_native  # requires #19002 \
  #

# select stdio_uart if no other stdio module is slected
ifeq (,$(filter $(STDIO_MODULES),$(USEMODULE)))
  USEMODULE += stdio_uart
endif

ifeq (,$(filter $(STDIO_LEGACY_MODULES),$(USEMODULE)))
  USEMODULE += stdio
endif

undefined reference to 'stdio_flush_rx' collect2: error: ld returned 1 exit status

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benpicco commented Apr 16, 2024

True, ethos would need a custom implementation.
Alternatively it could be ported to the new interface which would require something like #18066

@benpicco benpicco force-pushed the stdio_uart_add_flush_rx branch from 8d4c2e9 to acebfae Compare October 28, 2024 12:58
@maribu
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maribu commented Nov 21, 2024

bikeshedding: you'd "flush" output, "drain" input?

I think I'd rather go with a simple "clear" then instead, maybe "stdio_clear_input"?

@HendrikVE: Ping?

@HendrikVE HendrikVE force-pushed the stdio_uart_add_flush_rx branch from acebfae to 85984e7 Compare November 22, 2024 18:29
@HendrikVE HendrikVE changed the title sys/stdio_uart: add pseudomodule stdio_flush_rx sys/stdio_uart: add pseudomodule stdio_clear_rx Nov 22, 2024
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HendrikVE commented Nov 22, 2024

It's called stdio_clear_rx now. I tested it with stdio_uart (works) and stdio_rtt (does not work):

Not using stdio_clear_rx

2024-11-22 18:55:23,799 # main(): This is RIOT! (Version: 2025.01-devel-177-g307c2-stdio_uart_add_flush_rx)
2024-11-22 18:55:23,801 # Welcome to RIOT!
2024-11-22 18:55:23,802 # Enter a character:
h
2024-11-22 18:55:28,159 # You entered: 'h'
2024-11-22 18:55:28,161 # Enter a character:
2024-11-22 18:55:28,162 # You entered: '
2024-11-22 18:55:28,163 # '
2024-11-22 18:55:28,164 # Enter a character:
help
2024-11-22 18:55:29,583 # You entered: 'h'
2024-11-22 18:55:29,585 # Enter a character:
2024-11-22 18:55:29,587 # You entered: 'e'
2024-11-22 18:55:29,588 # Enter a character:
2024-11-22 18:55:29,590 # You entered: 'l'
2024-11-22 18:55:29,591 # Enter a character:
2024-11-22 18:55:29,593 # You entered: 'p'
2024-11-22 18:55:29,595 # Enter a character:
2024-11-22 18:55:29,596 # You entered: '
2024-11-22 18:55:29,596 # '
2024-11-22 18:55:29,598 # Enter a character:

Using stdio_clear_rx

2024-11-22 18:56:31,336 # main(): This is RIOT! (Version: 2025.01-devel-177-g307c2-stdio_uart_add_flush_rx)
2024-11-22 18:56:31,338 # Welcome to RIOT!
2024-11-22 18:56:31,339 # Enter a character:
h
2024-11-22 18:56:32,593 # You entered: 'h'
2024-11-22 18:56:32,595 # Enter a character:
help
2024-11-22 18:56:33,969 # You entered: 'h'
2024-11-22 18:56:33,971 # Enter a character:

Minimal program that I used:

USEMODULE += stdio_clear_rx

#include <stdio.h>
#include "stdio_base.h"

int main(void)
{
    char input_line[2];
    char input;

    while (true) {
        puts("Enter a character:");
        stdio_clear_rx();
        if (fgets(input_line, sizeof(input_line), stdin) != NULL) {
            if (sscanf(input_line, "%c", &input) != 1) {
                puts("Error on parsing user input!");
            }
            else {
                printf("You entered: '%c'\n", input);
            }
        }
        else {
            puts("Error on reading user input!");
        }
    }

    return 0;
}

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HendrikVE commented Nov 22, 2024

A tiny edit makes sure that stdio_clear_rx is useful when declared by pulling in stdin:

ifneq (,$(filter stdio_clear_rx,$(USEMODULE)))
  USEMODULE += stdin
endif

benpicco
benpicco reviewed Nov 22, 2024
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benpicco
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@HendrikVE HendrikVE force-pushed the stdio_uart_add_flush_rx branch 2 times, most recently from 059bb79 to aa13546 Compare November 26, 2024 17:05
@github-actions github-actions bot removed the Area: build system Area: Build system label Nov 26, 2024
@maribu
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maribu commented Nov 26, 2024

The PR and commit title needs an update now

@HendrikVE HendrikVE changed the title sys/stdio_uart: add pseudomodule stdio_clear_rx sys/stdio_uart: add stdio_clear_rx to clear stdin Nov 27, 2024
@HendrikVE HendrikVE changed the title sys/stdio_uart: add stdio_clear_rx to clear stdin sys/stdio_uart: add stdio_clear_rx for clearing stdin Nov 27, 2024
@HendrikVE HendrikVE force-pushed the stdio_uart_add_flush_rx branch from aa13546 to 6f9edfe Compare November 27, 2024 10:58
@HendrikVE HendrikVE changed the title sys/stdio_uart: add stdio_clear_rx for clearing stdin sys/stdio_uart: add stdio_clear_stdin Nov 27, 2024
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HendrikVE commented Nov 27, 2024

The PR and commit title needs an update now

Did so and also renamed to stdio_clear_stdin

@maribu maribu enabled auto-merge November 27, 2024 10:59
@maribu maribu added this pull request to the merge queue Nov 27, 2024
Merged via the queue into RIOT-OS:master with commit 67a22db Nov 27, 2024
@MrKevinWeiss MrKevinWeiss added this to the Release 2025.01 milestone Jan 20, 2025
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