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X && 0 and X & 0 are constant 0; X || 1 is constant 1 (#1399)

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Fixes #977
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Sylvie
2024-06-13 11:09:39 -04:00
committed by GitHub
parent c5c6cc9794
commit dfec7111e2
6 changed files with 65 additions and 2 deletions
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13
man/rgbasm.5
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@@ -218,6 +218,9 @@ knows its value.
This is generally always the case, unless a label is involved, as explained in the
.Sx SYMBOLS
section.
However, some operators can be constant even with non-constant operands, as explained in
.Sx Operators
further below.
.Pp
The instructions in the macro-language generally require constant expressions.
.Ss Numeric formats
@@ -306,13 +309,21 @@ equivalent to multiplying and dividing by 2 to the power of b, respectively.
.Pp
Comparison operators return 0 if the comparison is false, and 1 otherwise.
.Pp
Unlike in a lot of languages, and for technical reasons,
Unlike in many other languages, and for technical reasons,
.Nm
still evaluates both operands of
.Sq &&
and
.Sq || .
.Pp
The operators
.Sq &&
and
.Sq &
with a zero constant as either operand will be constant 0, and
.Sq ||
with a non-zero constant as either operand will be constant 1, even if the other operand is non-constant.
.Pp
.Ic \&!
returns 1 if the operand was 0, and 0 otherwise.
.Ss Fixed-point expressions