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Add BSF and BSR instruction wrappers
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This commit is contained in:
Aiken Harris
2026-06-01 00:36:52 +02:00
parent 7d8b33390a
commit 0aabc206a1
4 changed files with 108 additions and 0 deletions
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50
xtoskrnl/ar/amd64/cpufunc.cc
View File

@@ -617,6 +617,56 @@ AR::CpuFunctions::ReadWriteBarrier(VOID)
: "memory");
}
/**
* Performs a Bit Scan Forward instruction to locate the most significant set bit.
*
* @param Index
* Receives the zero-based index of the highest set bit when one is found.
*
* @param Mask
* Supplies the bitmap to scan.
*
* @return This routine returns TRUE when a set bit was found, otherwise FALSE.
*
* @since XT 1.0
*/
XTCDECL
BOOLEAN
AR::CpuFunctions::ScanForwardBit(OUT PULONG Index,
IN ULONG Mask)
{
/* Defer to the BSF instruction */
__asm__("bsfl %[Mask], %[Index]" : [Index] "=r" (*Index) : [Mask] "mr" (Mask));
/* Report whether the input had any bit set */
return Mask ? TRUE : FALSE;
}
/**
* Performs a Bit Scan Reverse instruction to locate the most significant set bit.
*
* @param Index
* Receives the zero-based index of the highest set bit when one is found.
*
* @param Mask
* Supplies the bitmap to scan.
*
* @return This routine returns TRUE when a set bit was found, otherwise FALSE.
*
* @since XT 1.0
*/
XTCDECL
BOOLEAN
AR::CpuFunctions::ScanReverseBit(OUT PULONG Index,
IN ULONG Mask)
{
/* Defer to the BSR instruction */
__asm__("bsrl %[Mask], %[Index]" : [Index] "=r" (*Index) : [Mask] "mr" (Mask));
/* Report whether the input had any bit set */
return Mask ? TRUE : FALSE;
}
/**
* Instructs the processor to set the interrupt flag.
*

50
xtoskrnl/ar/i686/cpufunc.cc
View File

@@ -587,6 +587,56 @@ AR::CpuFunctions::ReadWriteBarrier(VOID)
: "memory");
}
/**
* Performs a Bit Scan Forward instruction to locate the most significant set bit.
*
* @param Index
* Receives the zero-based index of the highest set bit when one is found.
*
* @param Mask
* Supplies the bitmap to scan.
*
* @return This routine returns TRUE when a set bit was found, otherwise FALSE.
*
* @since XT 1.0
*/
XTCDECL
BOOLEAN
AR::CpuFunctions::ScanForwardBit(OUT PULONG Index,
IN ULONG Mask)
{
/* Defer to the BSF instruction */
__asm__("bsfl %[Mask], %[Index]" : [Index] "=r" (*Index) : [Mask] "mr" (Mask));
/* Report whether the input had any bit set */
return Mask ? TRUE : FALSE;
}
/**
* Performs a Bit Scan Reverse instruction to locate the most significant set bit.
*
* @param Index
* Receives the zero-based index of the highest set bit when one is found.
*
* @param Mask
* Supplies the bitmap to scan.
*
* @return This routine returns TRUE when a set bit was found, otherwise FALSE.
*
* @since XT 1.0
*/
XTCDECL
BOOLEAN
AR::CpuFunctions::ScanReverseBit(OUT PULONG Index,
IN ULONG Mask)
{
/* Defer to the BSR instruction */
__asm__("bsrl %[Mask], %[Index]" : [Index] "=r" (*Index) : [Mask] "mr" (Mask));
/* Report whether the input had any bit set */
return Mask ? TRUE : FALSE;
}
/**
* Instructs the processor to set the interrupt flag.
*