ARM Compiler toolchain v4.1 for µVision Using the Compiler

Using the Inline and Embedded Assemblers of the ARM Compiler
7.22 Inline assembler register list operands in C and C++ code
A register list can contain a maximum of 16 operands. These operands can be virtual registers
or expression register operands.
The order that virtual registers and expression operands are specified in a register list is
significant. The register list operands are read or written in left-to-right order. The first operand
uses the lowest address, and subsequent operands use addresses formed by incrementing the
previous address by four. This behavior is in contrast to the usual operation of the LDM or STM
instructions where the lowest numbered physical register is always stored to the lowest memory
address. This difference in behavior is a consequence of the virtualization of registers.
An expression operand or virtual register can appear more than once in a register list and is used
each time it is specified.
The base register is updated, if specified. The update overwrites any value loaded into the base
register during a memory load operation.
Operating on User mode registers when in a privileged mode, by specifying ^ after a register
list, is not supported by the inline assembler.
7.22.1 See also
Concepts
• Inline assembler operands in C and C++ code on page 7-25
• Compiler support for inline assembly language on page 7-4.
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