http://www.emsps.com/oldtools/borpasv.htm Borland Pascal with Objects 7.01 - ... The only severe bug which was eliminated was the shift bug (SHL and SHR) for _longint_ operands with shift values between 16 and 31, which are unreliable if the code is executed on a 386+. On some processors they produce garbage -- on some processors they work. The implementors of 7.0 used a 386 opcode which would produce an undefined result under these circumstances. A solution to avoid this bug with 7.0 is to introduce a global variable. Save8086:byte; and surround parts of code using these SHIFT types (SHL or SHR) by Save8086:=Test8086; Test8086:=0; { Your code } Test8086:=Save8086; This will slow down the SHIFTs but they are correct because they will be executed using 16-bit registers with the correct TP 4.0-6.0 implementation. 谢谢 我已经找到答案了
longint是32位的，i shr 31如果结果不是1，那么就是0了。另，$90123456已经超出longint的最大范围，你使用Int64看看。—————————————————————————————————
宠辱不惊，看庭前花开花落，去留无意；毁誉由人，望天上云卷云舒，聚散任风。
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shr dx,cl调用前寄存器的值
ax 3456 dx 9012 cx 001F调用后
ax 685D dx 0000
Borland Pascal with Objects 7.01 - ... The only severe bug which was eliminated was the shift bug (SHL and SHR) for _longint_ operands with shift values between 16 and 31, which are unreliable if the code is executed on a 386+. On some processors they produce garbage -- on some processors they work. The implementors of 7.0 used a 386 opcode which would produce an undefined result under these circumstances. A solution to avoid this bug with 7.0 is to introduce a global variable. Save8086:byte; and surround parts of code using these SHIFT types (SHL or SHR) by Save8086:=Test8086; Test8086:=0; { Your code } Test8086:=Save8086; This will slow down the SHIFTs but they are correct because they will be executed using 16-bit registers with the correct TP 4.0-6.0 implementation. 谢谢 我已经找到答案了