34 lines
992 B
ArmAsm
34 lines
992 B
ArmAsm
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// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build arm64
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TEXT ·TrailingZeros64(SB),$0-16
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MOVD x+0(FP), R0
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RBIT R0, R0
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CLZ R0, R0 // return 64 if x == 0
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MOVD R0, ret+8(FP)
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RET
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TEXT ·MostSignificantOne64(SB),$0-16
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MOVD x+0(FP), R0
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CLZ R0, R0 // return 64 if x == 0
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MOVD $63, R1
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SUBS R0, R1, R0 // ret = 63 - CLZ
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BPL end
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MOVD $64, R0 // x == 0
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end:
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MOVD R0, ret+8(FP)
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RET
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