github.com/sagernet/gvisor@v0.0.0-20240428053021-e691de28565f/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  //go:build amd64
    16  // +build amd64
    17  
    18  TEXT ·TrailingZeros64(SB),$0-16
    19    BSFQ  x+0(FP), AX
    20    JNZ   end
    21    MOVQ  $64, AX
    22  end:
    23    MOVQ  AX, ret+8(FP)
    24    RET
    25  
    26  TEXT ·MostSignificantOne64(SB),$0-16
    27    BSRQ  x+0(FP), AX
    28    JNZ   end
    29    MOVQ  $64, AX
    30  end:
    31    MOVQ  AX, ret+8(FP)
    32    RET