RealView® Debugger Command Line Reference Guide 1.7.2. Data types

1.7.2. Data types

All symbols and expressions have an associated data type:

Source language modules can contain any valid C or C++ language data type.
Assembly language modules can contain variables with the types shown in Table 1.10. Some assemblers might have other types such as fixed-point. In addition, each symbol has an attribute that indicates whether a variable was defined in a code or data area. Also, the assembler can create arrays of these types in addition to structures (check with the assembler manufacturer for details).

Table 1.10. Equivalent RealView Debugger data types for ARM assembler

ARM assembler data type	Equivalent data type in RealView Debugger	Size (bytes)
byte	unsigned char	1
word	unsigned short int	2
long	unsigned long	4
8-byte long	long long	8
single-precision floating point	float	4
double-precision floating point	double	8
label	label	1

You can access a specific number of bytes in memory using the following predefined macros:

byte() to return an unsigned char
word() to return an unsigned short int
dword() to return an unsigned long.

Type conversion

The RealView Debugger performs data-type conversions under the following circumstances:

when two or more operands of different types appear in an expression, data type conversion is performed according to the rules of C or C++
when arguments are passed to a macro, the types of the passed arguments are converted to the types given in the macro function definition
when the data type of an operand is forced by user-specified type casting, it is converted
when a specific type is required by a command, the value is converted according to the rules of C/C++.

Type casting

Type casting forces the conversion of an expression to the specified data type. The contents of any variables that are referenced are not altered. Debugger expressions can be cast into different types using the following syntax:

(type_name) expression

Example 1.2 shows examples of casting different types.

Example 1.2. Casting symbols and expressions into different types

(char) prime             /* prime is cast to type char */
(float) 12               /* value is 12.0. (integer 12 in floating point) */
(int) sin(0.2)           /* value is 0, sin(0.2) is 0.198, truncates to 0 */
(int) ptr_char           /* the variable expression ptr_char is */
                         /* cast to type int */

The debugger can cast some expression types to an array type. Example 1.3 casts the constant expression 7 to an array of three characters starting at location 0x0007.

Example 1.3. Casting to an array

(char[3]) 7              /* address is 0x0007 */

This type of casting to an array can be used with the PRINTVALUE command. Assembly language structures can be displayed in a more meaningful form by using this technique. Table 1.11 lists additional special casting types. Arrays of hexadecimal types and pointers to hexadecimal types can also be used.

Table 1.11. Special casting types

Cast	Commands	Meaning
`(QUOTED STRING)` or `(Q S)`	PRINTVALUE	Show as "string."
`(INSTRUCTION ADDRESS)` or `(I A)`	All	Convert into a legal source-level address.
`(UNKNOWN TYPE)` or `(U T)`	All	Convert into a single byte.
`(HEX BYTE)` or `(H B)`	All	Show in hex bytes.
`(HEX WORD)` or `(H W)`	All	Show in 16 bit hex.
`(HEX DOUBLE WORD)` or `(H D)`	All	Show in 32 bit hex.

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1.7.2. Data types

Type conversion

Type casting

See also