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| Home > Using the Inline and Embedded Assemblers of the ARM Compiler > 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.