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Kernel: Optimize StorageDevice read and write function

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Use shift operator with log size instead of division while calculating
the index and len.
This commit is contained in:
Pankaj Raghav 2022-01-29 15:28:06 +05:30 committed by Idan Horowitz
parent 24c66b8442
commit 60aa4152e9
Notes: sideshowbarker 2024-07-18 05:01:22 +09:00 
Author: https://github.com/Panky-codes
Commit: https://github.com/SerenityOS/serenity/commit/60aa4152e94
Pull-request: https://github.com/SerenityOS/serenity/pull/12198
Reviewed-by: https://github.com/IdanHo
1 changed files with 6 additions and 6 deletions
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12
Kernel/Storage/StorageDevice.cpp
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@ -29,9 +29,9 @@ StringView StorageDevice::class_name() const
ErrorOr<size_t> StorageDevice::read(OpenFileDescription&, u64 offset, UserOrKernelBuffer& outbuf, size_t len)
{
u64 index = offset / block_size();
size_t whole_blocks = len / block_size();
size_t remaining = len % block_size();
u64 index = offset >> block_size_log();
size_t whole_blocks = len >> block_size_log();
size_t remaining = len - (whole_blocks << block_size_log());
// PATAChannel will chuck a wobbly if we try to read more than PAGE_SIZE
// at a time, because it uses a single page for its DMA buffer.
@ -91,9 +91,9 @@ bool StorageDevice::can_read(const OpenFileDescription&, u64 offset) const
ErrorOr<size_t> StorageDevice::write(OpenFileDescription&, u64 offset, const UserOrKernelBuffer& inbuf, size_t len)
{
u64 index = offset / block_size();
size_t whole_blocks = len / block_size();
size_t remaining = len % block_size();
u64 index = offset >> block_size_log();
size_t whole_blocks = len >> block_size_log();
size_t remaining = len - (whole_blocks << block_size_log());
// PATAChannel will chuck a wobbly if we try to write more than PAGE_SIZE
// at a time, because it uses a single page for its DMA buffer.