diff options
author | 2016-06-03 03:33:22 +0000 | |
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committer | 2016-06-03 03:33:23 +0000 | |
commit | da27230f80795d0028333713f036d44c53cb0e68 (patch) | |
tree | b3d379eaf000adf72b36cb01cdf4d79c3e3f064c /qemu/roms/ipxe/src/arch/i386/include/bits/strings.h | |
parent | 0e68cb048bb8aadb14675f5d4286d8ab2fc35449 (diff) | |
parent | 437fd90c0250dee670290f9b714253671a990160 (diff) |
Merge "These changes are the raw update to qemu-2.6."
Diffstat (limited to 'qemu/roms/ipxe/src/arch/i386/include/bits/strings.h')
-rw-r--r-- | qemu/roms/ipxe/src/arch/i386/include/bits/strings.h | 48 |
1 files changed, 46 insertions, 2 deletions
diff --git a/qemu/roms/ipxe/src/arch/i386/include/bits/strings.h b/qemu/roms/ipxe/src/arch/i386/include/bits/strings.h index 092bcb593..453545f00 100644 --- a/qemu/roms/ipxe/src/arch/i386/include/bits/strings.h +++ b/qemu/roms/ipxe/src/arch/i386/include/bits/strings.h @@ -1,7 +1,51 @@ #ifndef _BITS_STRINGS_H #define _BITS_STRINGS_H -FILE_LICENCE ( GPL2_OR_LATER ); +FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); + +/** + * Find first (i.e. least significant) set bit + * + * @v value Value + * @ret lsb Least significant bit set in value (LSB=1), or zero + */ +static inline __attribute__ (( always_inline )) int __ffsl ( long value ) { + long lsb_minus_one; + + /* If the input value is zero, the BSF instruction returns + * ZF=0 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__ ( "bsfl %1, %0" + : "=r" ( lsb_minus_one ) + : "rm" ( value ) ); + return ( lsb_minus_one + 1 ); + } else { + return 0; + } +} + +/** + * Find first (i.e. least significant) set bit + * + * @v value Value + * @ret lsb Least significant bit set in value (LSB=1), or zero + */ +static inline __attribute__ (( always_inline )) int __ffsll ( long long value ){ + unsigned long high = ( value >> 32 ); + unsigned long low = ( value >> 0 ); + + if ( low ) { + return ( __ffsl ( low ) ); + } else if ( high ) { + return ( 32 + __ffsl ( high ) ); + } else { + return 0; + } +} /** * Find last (i.e. most significant) set bit @@ -13,7 +57,7 @@ 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. + * ZF=0 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. |