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| author | Robin Haberkorn <robin.haberkorn@googlemail.com> | 2025-04-10 03:41:28 +0300 |
|---|---|---|
| committer | Robin Haberkorn <robin.haberkorn@googlemail.com> | 2025-04-10 03:50:48 +0300 |
| commit | 9e82d5ee56d258d33f59eb6fdcc363d8c0c47b4c (patch) | |
| tree | a1c75db760bfd57c4051cc54352ed7eb65772fd3 /doc | |
| parent | c462509adfd68e8b849b8a6713360fb4f9026578 (diff) | |
| download | sciteco-9e82d5ee56d258d33f59eb6fdcc363d8c0c47b4c.tar.gz | |
testsuite: check whether comparisons for equality really work with the `a-b"=` idiom
* There might theoretically be problems with the uncommon one's complement or magnitude
representation of negative integers, but it's practically impossible to meet those in
the wild.
* Still, we do some checks now, so we will at least notice any exotic architectures.
* Also, documented the `a^#b"=` idiom for checking for equality.
It's longer to type, but faster and will also work for floats.
For floats it will be the only permissible idiom for checking for bitwise equality
as `a-b` can be 0 even if a!=b (if the difference is very small).
Changing the `-` semantics is out of the question.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/sciteco.7.template | 28 |
1 files changed, 16 insertions, 12 deletions
diff --git a/doc/sciteco.7.template b/doc/sciteco.7.template index b43b4d2..4736be2 100644 --- a/doc/sciteco.7.template +++ b/doc/sciteco.7.template @@ -2323,7 +2323,7 @@ in portable macros. This is not the case, for instance when working with environment registers. .TP -.SCITECO_TOPIC """S" """T" +.SCITECO_TOPIC """S" """T" success true .IB n \(dqS .TQ .IB n \(dqT @@ -2332,7 +2332,7 @@ success (or truth). Therefore it is equivalent to a check for less than zero (negative). .TP -.SCITECO_TOPIC """F" """U" +.SCITECO_TOPIC """F" """U" failure false .IB n \(dqF .TQ .IB n \(dqU @@ -2341,17 +2341,19 @@ failure (or falsehood). Therefore it is equivalent to a check for greater than or equal to zero (non-negative). .TP -.SCITECO_TOPIC """E" """=" +.SCITECO_TOPIC """E" """=" equal .IB n \(dqE .TQ .IB n \(dq= Applies if \fIn\fP equals zero. .br -To check two values \fIa\fP and \fIb\fP for equality you -will commonly write: -.IB a - b \(dq= +The classic idiom for checking two values \fIa\fP and \fIb\fP for equality is +.IB a - b \(dq=\c +, but writing +.IB a ^# b \(dq= +(XOR operator) is faster. .TP -.SCITECO_TOPIC """G" """>" +.SCITECO_TOPIC """G" """>" greater .IB n \(dqG .TQ .IB n \(dq> @@ -2361,7 +2363,7 @@ To check if a value \fIa\fP is greater than a value \fIb\fP you will commonly write: .IB a - b \(dq> .TP -.SCITECO_TOPIC """L" """<" +.SCITECO_TOPIC """L" """<" lesser .IB n \(dqL .TQ .IB n \(dq< @@ -2371,13 +2373,15 @@ To check if a value \fIa\fP is less than a value \fIb\fP you will commonly write: .IB a - b \(dq< .TP -.SCITECO_TOPIC """N" +.SCITECO_TOPIC """N" unequal .IB n \(dqN Applies if \fIn\fP is not zero. .br -To check two values \fIa\fP and \fIb\fP for inequality you -will commonly write: -.IB a - b \(dqN +The classic idiom for checking two values \fIa\fP and \fIb\fP for inequality is +.IB a - b \(dqN\c +, but writing +.IB a ^# b \(dqN +(XOR operator) is faster. .TP .SCITECO_TOPIC """R" .IB n \(dqR |