I have been testing all short sequences of code and found an error in the last part of Chapter 7 where I planned to use movsx with an immediate 32 bit field to prepare a mask. The movsx instruction allows a register or memory 32 bit field to be sign-extended but not an immediate field. The fix looked a little ugly and sign extension is not an elegant solution so I posted an better solution in the Chapter 7 errata page.
The better solution is shifting the rax register right 29 bits, followed by shifting it left 29 bits. This is more generally applicable. More importantly it actually works.
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