ARM Compiler armasm User Guide : 12.19 Unary operators

12.19 Unary operators

Unary operators return a string, numeric, or logical value. They have higher precedence than other operators and are evaluated first.

A unary operator precedes its operand. Adjacent operators are evaluated from right to left.

The following table lists the unary operators that return strings:

Table 12-1 Unary operators that return strings

Operator	Usage	Description
`:CHR:`	`:CHR:A`	Returns the character with ASCII code A.
`:LOWERCASE:`	`:LOWERCASE:string`	Returns the given string, with all uppercase characters converted to lowercase.
`:REVERSE_CC:`	`:REVERSE_CC:cond_code`	Returns the inverse of the condition code in `cond_code`, or an error if `cond_code` does not contain a valid condition code.
`:STR:`	`:STR:A`	In A32 and T32 code, returns an 8-digit hexadecimal string corresponding to a numeric expression, or the string `"T"` or `"F"`" if used on a logical expression. In A64 code, returns a 16-digit hexadecimal string.
`:UPPERCASE:`	`:UPPERCASE:string`	Returns the given string, with all lowercase characters converted to uppercase.

The following table lists the unary operators that return numeric values:

Table 12-2 Unary operators that return numeric or logical values

Operator	Usage	Description
`?`	`?A`	Number of bytes of code generated by line defining symbol A.
`+` and `-`	`+A` `-A`	Unary plus. Unary minus. + and – can act on numeric and PC-relative expressions.
`:BASE:`	`:BASE:A`	If A is a PC-relative or register-relative expression, `:BASE:` returns the number of its register component. `:BASE:` is most useful in macros.
`:CC_ENCODING:`	`:CC_ENCODING:cond_code`	Returns the numeric value of the condition code in `cond_code`, or an error if `cond_code` does not contain a valid condition code.
`:DEF:`	`:DEF:A`	{`TRUE`} if A is defined, otherwise {`FALSE`}.
`:INDEX:`	`:INDEX:A`	If A is a register-relative expression, `:INDEX:` returns the offset from that base register. `:INDEX:` is most useful in macros.
`:LEN:`	`:LEN:A`	Length of string A.
`:LNOT:`	`:LNOT:A`	Logical complement of A.
`:NOT:`	`:NOT:A`	Bitwise complement of A (`~` is an alias, for example `~A`).
`:RCONST:`	`:RCONST:Rn`	Number of register. In A32/T32 code, 0-15 corresponds to R0-R15. In A64 code, 0-30 corresponds to W0-W30 or X0-X30.

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