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[SPCA] Fix various errors

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Janis Hutz
2026-01-23 10:33:49 +01:00
parent b86fd00a60
commit 25b3381294
15 changed files with 36 additions and 23 deletions
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semester3/spca/parts/00_asm/03_operations/02_condition-codes.tex
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@@ -11,12 +11,13 @@ The following condition codes were covered in the lecture (operation: \texttt{t
\content{Explicit computation}
In the below explanations, we always assume \texttt{src2 = b} and \texttt{src1 = a}
To explicitly compute them, we can use the \texttt{cmpX src2, src1} instruction (with X again any of the size postfixes),
To explicitly compute them, we can use the \texttt{cmpX src2, src1} (i.e. for easier understanding, \texttt{cmpX b, a}) instruction (with X again any of the size postfixes),
that essentially computes $(a - b)$ without setting a destination register.
When we execute that instruction, \texttt{CF} is set if \texttt{a < b} (unsigned), \texttt{ZF} is set if \texttt{a == b}, \texttt{SF} is set if \texttt{a < b} (signed)
and \texttt{OF} is set as above, where \texttt{t = a - b}.
Another instruction that is used is \texttt{testX src2, src1} (X again a size postfix), and acts like computing \texttt{a \& b} and where \texttt{ZF} is set if \texttt{a \& b == 0}
Another instruction that is used is \texttt{testX src2, src1} (X again a size postfix, easier: \texttt{testX b, a}), and acts like computing \texttt{a \& b} and where \texttt{ZF} is set if \texttt{a \& b == 0}
and \texttt{SF} is set if \texttt{a \& b < 0}.
\content{Zeroing register} We can use a move instruction, but that is less efficient than using \texttt{xorl reg, reg}, where \texttt{reg} is the 32-bit version of the reg we want to zero.