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doc: Remove some ugliness from the win64 section

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Clean up the formatting of the Win64 examples.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin 2012-02-25 15:50:32 -08:00
parent c65035ecdb
commit 38e57c5084
1 changed files with 9 additions and 8 deletions
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17
doc/nasmdoc.src
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@ -5415,20 +5415,21 @@ While \c{REL} takes good care of RIP-relative addressing, there is one
aspect that is easy to overlook for a Win64 programmer: indirect
references. Consider a switch dispatch table:
\c jmp QWORD[dsptch+rax*8]
\c jmp qword [dsptch+rax*8]
\c ...
\c dsptch: dq case0
\c dq case1
\c ...
Even novice Win64 assembler programmer will soon realize that the code
Even a novice Win64 assembler programmer will soon realize that the code
is not 64-bit savvy. Most notably linker will refuse to link it with
"\c{'ADDR32' relocation to '.text' invalid without
/LARGEADDRESSAWARE:NO}". So [s]he will have to split jmp instruction as
following:
\c 'ADDR32' relocation to '.text' invalid without /LARGEADDRESSAWARE:NO
So [s]he will have to split jmp instruction as following:
\c lea rbx,[rel dsptch]
\c jmp QWORD[rbx+rax*8]
\c jmp qword [rbx+rax*8]
What happens behind the scene is that effective address in \c{lea} is
encoded relative to instruction pointer, or in perfectly
@ -5441,7 +5442,7 @@ to current process, which kind of undermines the idea of sharing .dll.
But no worry, it's trivial to fix:
\c lea rbx,[rel dsptch]
\c add rbx,QWORD[rbx+rax*8]
\c add rbx,[rbx+rax*8]
\c jmp rbx
\c ...
\c dsptch: dq case0-dsptch
@ -5456,7 +5457,7 @@ acquainted with PE-COFF format base address denotes start of
these image-relative references:
\c lea rbx,[rel dsptch]
\c mov eax,DWORD[rbx+rax*4]
\c mov eax,[rbx+rax*4]
\c sub rbx,dsptch wrt ..imagebase
\c add rbx,rax
\c jmp rbx