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runtime/mpallocbits.go pallocBits.summarize function problem #39990

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web3creator opened this issue Jul 2, 2020 · 6 comments
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runtime/mpallocbits.go pallocBits.summarize function problem #39990

web3creator opened this issue Jul 2, 2020 · 6 comments
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@web3creator
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web3creator commented Jul 2, 2020 •
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golang1.14.3 linux amd64

example

   var p1 pageBits
p1[0]=0b00000000_00000000_00000000_00000001_00000000_00000000_00000000_00000000
p1[1]=0b00000000_00000000_00000000_00000001_00000000_00000000_00000000_11110000
p1[2]=0b00000000_00000000_00000000_00000001_00000000_00000000_00000000_11110000
p1[3]=0b00000000_00000000_00000000_00000001_00000000_00000000_00000000_11110000
p1[4]=0b00000000_00000000_00000000_00000001_00000000_00000000_00000000_11110000
p1[5]=0b00000000_00000000_00000000_00000001_00000000_00000000_00000000_00000000
p1[6]=0b00000000_00000000_00000000_00000000_00000000_00000000_00000000_11110000
p1[7]=0b00000000_00000000_00000000_00000001_00000000_00000000_00000000_01010000
    p1summarize()
   
   // return start:32   max:63  end:31
   // I think it should return start:32 max:88 end31
  // What is the strategy of this summarizefunction when calculating max
@web3creator web3creator changed the title about pallocBits.summarize function problem untime/mpallocbits.go pallocBits.summarize function problem Jul 2, 2020
@web3creator web3creator changed the title untime/mpallocbits.go pallocBits.summarize function problem runtime/mpallocbits.go pallocBits.summarize function problem Jul 2, 2020
@ianlancetaylor
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CC @mknyszek

@web3creator
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I think the function summarize has a bug, @mknyszek think?

@randall77
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Why would max be 88? The max is 63. The high 31 zeroes of p1[4] and the low 32 zeroes of p1[5].

@web3creator
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Why would max be 88? The max is 63. The high 31 zeroes of p1[4] and the low 32 zeroes of p1[5].

@randall77 ， I think it should be The high 56 zeroes of p1[6] and the low 32 zeroes of p1[5].Where do I understand the deviation?

@randall77
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The bits are ordered from low to high in each word, then in increasing word index. So the high 56 zeroes of p1[6] are adjacent to the low 4 zeroes of p1[7], not the low 32 zeroes p1[5].

This doesn't look like a bug to me.

@web3creator
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@randall77 Thank you for your answer, you're right.

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@ianlancetaylor @randall77 @gopherbot @web3creator