From d36e814b8aad0dc15386180245efb3f5cb8b8386 Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Sun, 27 Apr 2014 16:11:44 +0100 Subject: [libc] Add flsll() Signed-off-by: Michael Brown --- src/arch/i386/include/bits/strings.h | 50 ++++++++++++++++++++++++++++++++++ src/arch/x86/include/bits/strings.h | 31 --------------------- src/arch/x86_64/include/bits/strings.h | 42 ++++++++++++++++++++++++++++ 3 files changed, 92 insertions(+), 31 deletions(-) create mode 100644 src/arch/i386/include/bits/strings.h delete mode 100644 src/arch/x86/include/bits/strings.h create mode 100644 src/arch/x86_64/include/bits/strings.h (limited to 'src/arch') diff --git a/src/arch/i386/include/bits/strings.h b/src/arch/i386/include/bits/strings.h new file mode 100644 index 000000000..092bcb593 --- /dev/null +++ b/src/arch/i386/include/bits/strings.h @@ -0,0 +1,50 @@ +#ifndef _BITS_STRINGS_H +#define _BITS_STRINGS_H + +FILE_LICENCE ( GPL2_OR_LATER ); + +/** + * Find last (i.e. most significant) set bit + * + * @v value Value + * @ret msb Most significant bit set in value (LSB=1), or zero + */ +static inline __attribute__ (( always_inline )) int __flsl ( long value ) { + long msb_minus_one; + + /* If the input value is zero, the BSR instruction returns + * ZF=1 and leaves an undefined value in the output register. + * Perform this check in C rather than asm so that it can be + * omitted in cases where the compiler is able to prove that + * the input is non-zero. + */ + if ( value ) { + __asm__ ( "bsrl %1, %0" + : "=r" ( msb_minus_one ) + : "rm" ( value ) ); + return ( msb_minus_one + 1 ); + } else { + return 0; + } +} + +/** + * Find last (i.e. most significant) set bit + * + * @v value Value + * @ret msb Most significant bit set in value (LSB=1), or zero + */ +static inline __attribute__ (( always_inline )) int __flsll ( long long value ){ + unsigned long high = ( value >> 32 ); + unsigned long low = ( value >> 0 ); + + if ( high ) { + return ( 32 + __flsl ( high ) ); + } else if ( low ) { + return ( __flsl ( low ) ); + } else { + return 0; + } +} + +#endif /* _BITS_STRINGS_H */ diff --git a/src/arch/x86/include/bits/strings.h b/src/arch/x86/include/bits/strings.h deleted file mode 100644 index 62e0fbfba..000000000 --- a/src/arch/x86/include/bits/strings.h +++ /dev/null @@ -1,31 +0,0 @@ -#ifndef _BITS_STRINGS_H -#define _BITS_STRINGS_H - -FILE_LICENCE ( GPL2_OR_LATER ); - -/** - * Find last (i.e. most significant) set bit - * - * @v value Value - * @ret msb Most significant bit set in value (LSB=1), or zero - */ -static inline __attribute__ (( always_inline )) int __flsl ( long value ) { - long msb_minus_one; - - /* If the input value is zero, the BSR instruction returns - * ZF=1 and leaves an undefined value in the output register. - * Perform this check in C rather than asm so that it can be - * omitted in cases where the compiler is able to prove that - * the input is non-zero. - */ - if ( value ) { - __asm__ ( "bsr %1, %0" - : "=r" ( msb_minus_one ) - : "rm" ( value ) ); - return ( msb_minus_one + 1 ); - } else { - return 0; - } -} - -#endif /* _BITS_STRINGS_H */ diff --git a/src/arch/x86_64/include/bits/strings.h b/src/arch/x86_64/include/bits/strings.h new file mode 100644 index 000000000..6ee99a500 --- /dev/null +++ b/src/arch/x86_64/include/bits/strings.h @@ -0,0 +1,42 @@ +#ifndef _BITS_STRINGS_H +#define _BITS_STRINGS_H + +FILE_LICENCE ( GPL2_OR_LATER ); + +/** + * Find last (i.e. most significant) set bit + * + * @v value Value + * @ret msb Most significant bit set in value (LSB=1), or zero + */ +static inline __attribute__ (( always_inline )) int __flsll ( long long value ){ + long long msb_minus_one; + + /* If the input value is zero, the BSR instruction returns + * ZF=1 and leaves an undefined value in the output register. + * Perform this check in C rather than asm so that it can be + * omitted in cases where the compiler is able to prove that + * the input is non-zero. + */ + if ( value ) { + __asm__ ( "bsrq %1, %0" + : "=r" ( msb_minus_one ) + : "rm" ( value ) ); + return ( msb_minus_one + 1 ); + } else { + return 0; + } +} + +/** + * Find last (i.e. most significant) set bit + * + * @v value Value + * @ret msb Most significant bit set in value (LSB=1), or zero + */ +static inline __attribute__ (( always_inline )) int __flsl ( long value ) { + + return __flsll ( value ); +} + +#endif /* _BITS_STRINGS_H */ -- cgit v1.2.3-55-g7522