Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Fix SD info64 : info.usedBytes calculation giving weird result #8445

Merged
merged 1 commit into from
Jan 10, 2022
Merged

Fix SD info64 : info.usedBytes calculation giving weird result #8445

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion libraries/SDFS/src/SDFS.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -101,7 +101,7 @@ class SDFSImpl : public FSImpl
info.pageSize = 0; // TODO ?
info.maxPathLength = 255; // TODO ?
info.totalBytes =_fs.vol()->clusterCount() * info.blockSize;
info.usedBytes = info.totalBytes - (_fs.vol()->freeClusterCount() * _fs.vol()->bytesPerCluster());
info.usedBytes = (_fs.vol()->clusterCount() - _fs.vol()->freeClusterCount()) * info.blockSize;
Copy link
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

When I manually factor things I think this change is mathematically the same as the existing code.

info.usedBytes = info.totalBytes - (_fs.vol()->freeClusterCount() * _fs.vol()->bytesPerCluster());
info.totalBytes =_fs.vol()->clusterCount() * info.blockSize;
info.blockSize = _fs.vol()->bytesPerCluster();

So,

info.usedBytes = (_fs.vol()->clusterCount() * _fs.vol()->bytesPerCluster()) - (_fs.vol()->freeClusterCount() * _fs.vol()->bytesPerCluster());

Factor out the bpc and you get

info.usedBytes = (_fs.vol()->clusterCount() - _fs.vol()->freeClusterCount() ) * _fs.vol()->bytesPerCluster();

which is the patch's rewrite, no?

Copy link
Contributor Author

@luc-github luc-github Jan 9, 2022 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I do agree about calculation , but the fact is the current does not give the correct result.
Seems overflow happen.

Could be a type issue when doing calculation ?

Copy link
Contributor Author

@luc-github luc-github Jan 9, 2022 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

with figures it is may be more clear:

#include <SPI.h>
#include <SD.h>
#include <SDFS.h>
void setup(){
    Serial.begin(115200);
    if(!SD.begin(5)){
        Serial.println("Card Mount Failed");
        return;
    }
	FSInfo64 info;
	 if (!SDFS.info64(info)) {
		 Serial.println("Size unkown");
            return ;
        }
    Serial.printf("\nTotal space: %lluMB\n", info.totalBytes / (1024 * 1024));
    Serial.printf("Used space: %lluMB\n", info.usedBytes / (1024 * 1024));
}

void loop(){}

Without PR
Total space: 3760MB
Used space: 4929MB =>Wrong

With PR
Total space: 3760MB
Used space: 833MB =>Correct

return true;
}

Expand Down