H8/300-Regs - Using as
Description: Using as

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##### 9.12.2.2 Register Names

You can use predefined symbols of the form ‘`rnh`’ and ‘`rnl`’ to refer to the H8/300 registers as sixteen 8-bit general-purpose registers. n is a digit from ‘`0`’ to ‘`7`’); for instance, both ‘`r0h`’ and ‘`r7l`’ are valid register names.

You can also use the eight predefined symbols ‘`rn`’ to refer to the H8/300 registers as 16-bit registers (you must use this form for addressing).

On the H8/300H, you can also use the eight predefined symbols ‘`ern`’ (‘`er0`’ ... ‘`er7`’) to refer to the 32-bit general purpose registers.

The two control registers are called `pc` (program counter; a 16-bit register, except on the H8/300H where it is 24 bits) and `ccr` (condition code register; an 8-bit register). `r7` is used as the stack pointer, and can also be called `sp`.