github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/bits/uint64_arch_amd64_asm.s (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // +build amd64
    16  
    17  TEXT ·TrailingZeros64(SB),$0-16
    18    BSFQ  x+0(FP), AX
    19    JNZ   end
    20    MOVQ  $64, AX
    21  end:
    22    MOVQ  AX, ret+8(FP)
    23    RET
    24  
    25  TEXT ·MostSignificantOne64(SB),$0-16
    26    BSRQ  x+0(FP), AX
    27    JNZ   end
    28    MOVQ  $64, AX
    29  end:
    30    MOVQ  AX, ret+8(FP)
    31    RET