github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/time/muldiv_arm64.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  #include "funcdata.h"
    16  #include "textflag.h"
    17  
    18  // Documentation is available in parameters.go.
    19  //
    20  // func muldiv64(value, multiplier, divisor uint64) (uint64, bool)
    21  TEXT ·muldiv64(SB),NOSPLIT,$40-33
    22      GO_ARGS
    23      NO_LOCAL_POINTERS
    24      MOVD    value+0(FP), R0
    25      MOVD    multiplier+8(FP), R1
    26      MOVD    divisor+16(FP), R2
    27  
    28      UMULH   R0, R1, R3
    29      MUL     R0, R1, R4
    30  
    31      CMP     R2, R3
    32      BHS     overflow
    33  
    34      MOVD    R3, 8(RSP)
    35      MOVD    R4, 16(RSP)
    36      MOVD    R2, 24(RSP)
    37      CALL    ·divWW(SB)
    38      MOVD    32(RSP), R0
    39      MOVD    R0, result+24(FP)
    40      MOVD    $1, R0
    41      MOVB    R0, ok+32(FP)
    42      RET
    43  
    44  overflow:
    45      MOVD    ZR, result+24(FP)
    46      MOVB    ZR, ok+32(FP)
    47      RET