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Fix ** right-associativity, and clarify docs (#1566)

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Sylvie
2024-12-03 20:40:50 -05:00
committed by GitHub
parent 6982c8a116
commit 0b147c9386
3 changed files with 55 additions and 15 deletions
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37
man/rgbasm.5
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@@ -309,26 +309,35 @@ is equivalent to
.Pp .Pp
You can also use symbols, which are implicitly replaced with their value. You can also use symbols, which are implicitly replaced with their value.
.Ss Operators .Ss Operators
A great number of operators you can use in expressions are available (listed from highest to lowest precedence): You can use these operators in numeric expressions (listed from highest to lowest precedence):
.Bl -column -offset indent "!= == <= >= < >" .Bl -column -offset indent "!= == <= >= < >"
.It Sy Operator Ta Sy Meaning .It Sy Operator Ta Sy Meaning
.It Li \&( \&) Ta Precedence override .It Li \&( \&) Ta Grouping
.It Li FUNC() Ta Built-in function call .It Li FUNC() Ta Built-in function call
.It Li ** Ta Exponent .It Li ** Ta Exponentiation
.It Li ~ + - Ta Unary complement/plus/minus .It Li + - ~ \&! Ta Unary plus, minus (negation), complement (bitwise negation), and Boolean negation
.It Li * / % Ta Multiply/divide/modulo .It Li * / % Ta Multiplication, division, and modulo (remainder)
.It Li << Ta Shift left .It Li << >> >>> Ta Bit shifts (left, sign-extended right, zero-extended right)
.It Li >> Ta Signed shift right (sign-extension) .It Li & \&| ^ Ta Bitwise AND/OR/XOR
.It Li >>> Ta Unsigned shift right (zero-extension) .It Li + - Ta Addition and subtraction
.It Li & \&| ^ Ta Binary and/or/xor .It Li == != < > <= >= Ta Comparisons
.It Li + - Ta Add/subtract .It Li && Ta Boolean AND
.It Li != == <= >= < > Ta Comparison .It Li || Ta Boolean OR
.It Li && || Ta Boolean and/or
.It Li \&! Ta Unary not
.El .El
.Pp .Pp
.Sq **
raises a number to a non-negative power. It is the only
.Em right-associative
operator, meaning that
.Ql p ** q ** r
is equal to
.Ql p ** (q ** r) ,
not
.Ql (p ** q) ** r .
All other binary operators are left-associative.
.Pp
.Sq ~ .Sq ~
complements a value by inverting all its bits. complements a value by inverting all 32 of its bits.
.Pp .Pp
.Sq % .Sq %
is used to get the remainder of the corresponding division, so that is used to get the remainder of the corresponding division, so that

2
src/asm/parser.y
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@@ -140,7 +140,7 @@
%left OP_SHL OP_SHR OP_USHR %left OP_SHL OP_SHR OP_USHR
%left OP_MUL OP_DIV OP_MOD %left OP_MUL OP_DIV OP_MOD
%precedence NEG // applies to unary OP_LOGICNOT, OP_ADD, OP_SUB, OP_NOT %precedence NEG // applies to unary OP_LOGICNOT, OP_ADD, OP_SUB, OP_NOT
%left OP_EXP %right OP_EXP
// Assignment operators (only for variables) // Assignment operators (only for variables)
%token POP_EQUAL "=" %token POP_EQUAL "="

31
test/asm/operator-associativity.asm Normal file
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@@ -0,0 +1,31 @@
MACRO setup
def result = (\2) \1 (\3) \1 (\4)
def leftgroup = ((\2) \1 (\3)) \1 (\4)
def rightgroup = (\2) \1 ((\3) \1 (\4))
ENDM
MACRO left
setup \#
ASSERT result == leftgroup && result != rightgroup
ENDM
MACRO right
setup \#
ASSERT result == rightgroup && result != leftgroup
ENDM
left /, 24, 6, 2
left %, 22, 13, 5
right **, 2, 3, 2
left ==, 0, 1, 2
left !=, 1, 1, 2
left <, 1, 2, 2
left >, 2, 2, 1
left <=, 1, 3, 2
left >=, 2, 3, 1
left <<, 1, 2, 2
left >>, 16, 2, 2
left >>>, 16, 2, 2