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request to support sdcc mcs51 declarations (__sfr, __sbit, etc) #2499
Description
sdcc, which is quite popular open-source, free embedded compiler, uses special extensions for intel 8051 (aka mcs51) define special function registers and other similar things (like code, ram space, etc)
e.g.
__sfr __at (0xC0) P4 ;
__sbit __at (0xC0) P4_0 ;
extensions are discussed further in section 3.5.1 of sdcc user guide:
http://sdcc.sourceforge.net/doc/sdccman.pdf
We are using sdcc for a new platformio intel-mcs51 platform, (https://github.com/platformio/platform-intel_mcs51) and would love to be able to use the vscode cpptools intellisense here to peek at register definitions, etc.
I see this was previously discussed and rejected for keil C51 compiler at #1821, however I think this is quite different in that Keil is closed/proprietary/non-free (and has it's own ide) whereas sdcc is completely free and opensource, and sdcc+platformio+vscode+cpptools are getting really close to making full open-source ide stack
tagging a few stakeholders:
Ivan Kravets (@ivankravets) Philipp Klaus Krause (@spth) Chronos (@znhocn)
Activity
[-]request to support sdcc mcs51 declarations (__sfr, __sbit[/-][+]request to support sdcc mcs51 declarations (__sfr, __sbit, etc)[/+]anders-liu commentedon Jan 28, 2019
Vote
dimka-rs commentedon Feb 3, 2019
Probably, STM8 interrupt case falls here too. ISR is declared this way:
void tim4_isr(void) __interrupt(ITC_IRQ_TIM4_OVF)vscode expects
{instead of__interrupt.wdgConsulting commentedon Apr 16, 2019
Similar, for SDCC STM8
void TrapHandler (void) __trap {
...
}
cocus commentedon May 2, 2019
Hi, I would vote for the same thing. It doesn't need to be MCS51 specific; since __sfr and __at are also used in other platforms (at least, I'm using them in Z80/HD64180/Z180).
leoshusar commentedon May 31, 2020
I would really appreciate this support, I am programming for SDCC and if I use
void IRQHandler __interrupt() { }, it then messes up the whole document error checking.SarangKulkarni commentedon Jul 18, 2020
My workaround for this is to edit
.vscode/c_cpp_properties.jsonand edit the"defines"array so that intellisense thinks that the additional keywords are pre-processor defines. Something like:When you mouseover
__interrupt(nn)in your actual code, you will see some garbage tooltip of"
#define __interrupt(IntelliSense_Hack)" but that's only assumed by vscode and not by sdcc / your actual compiler, so the code compiles correctly.sean-mcmanus commentedon Jul 22, 2020
I've filed a feature request on VS (if they add support, we would probably get it too due to shared code): https://developercommunity.visualstudio.com/idea/1122536/c-intellisense-request-to-support-sdcc-mcs51-decla.html
5 remaining items
maxgerhardt commentedon Mar 10, 2021
Same here, upvoted this issue. I've also created a more general issue since I didn't feel the title and content wasn't general enough -- see link above.
It would be really great to see SDCC compiler support in VSCode!
anyin233 commentedon Apr 1, 2021
There are still some probrems with intellsense, some key words like
P0_1still cannot be determined correctly. Just like thismpeschke commentedon Oct 14, 2022
When I added the sdcc include path to my project, Visual Studio Code's default c_cpp_properties.json came with a default "cStandard: c17" setting. Since sdcc itself is based on C99 (https://sdcc.sourceforge.net/), changing it to c99 satisfies Intellisense for my project files:
However, it still complains about the sdcc internal implementation:
Not a solution, but a workaround until sdcc is fully supported by VSC.
spth commentedon Oct 16, 2022
Actually, the current SDCC release 4.2.0 supports C11 by default (and C17 is just a clarification of C11).
onlyloveonlyu commentedon Nov 4, 2022
At present, I have achieved this through this compromise plan
wc7086 commentedon Oct 28, 2023
Is there a patch or dirty hack that does this?
GsoyG commentedon Nov 30, 2023
Borrow the above method:
You can define it in the defines of c_cpp_properties.json
This only affects IntelliSense.
ultrapoci commentedon Jan 30, 2024
I've added this configuration to my workspace:
But the keyword
__interruptis still flagged as an error:What did I do wrong?
bobbrow commentedon Jan 30, 2024
You will likely need to set the define as
"__interrupt="to make IntelliSense skip over it (the=is important so that it is assigned an empty string value instead of the number1). If that still doesn't clear the error, please run theC/C++: Log Diagnosticscommand while the file is opened and share the output so we can determine why the define is not being used.bobbrow commentedon Jan 31, 2024
Nicholas Pini (@ultrapoci) I saw an update from you which seems to be deleted now (?). Based on what you said, the problem is that you are using the clangd extension for IntelliSense and it does not consider the
c_cpp_properties.jsonconfigurations at all. I am not aware of a way to achieve what you want if you are using clangd for IntelliSense.ultrapoci commentedon Jan 31, 2024
Yeah, sorry, for some reason I thought I was on the clangd repo, sorry for the dumb mistake. But I've also experimented with the C/C++ extension and your suggestion worked. It was also helpful because I was able to solve the issue in clangd as well, by passing
-D__interruptflag to the compiler. Now the word is treated as an empty macro. Thank you!rushairer commentedon Feb 12, 2024
Vote
lgzcoollg commentedon Apr 17, 2024
I get the same wrong mention:
when I build :
here is my setting:
github0null commentedon Aug 13, 2025
The problem can be solved by using the forceinclude function to include the following files and add a C define
__VSCODE_CPPTOOLto enable it.https://github.com/github0null/eide/blob/master/res/data/builtin_headers/lint_sdcc.h
I have integrated it into the plugin I developed. (https://github.com/github0null/eide)