Contents|Index|Previous|Next H8/300 dependent features See the following documentation for the Hitachi H8/300 architecture’s features and options for the assembler. Options for H8/300 Syntax for H8/300 Special characters for H8/300 Register names for H8/300 Addressing modes for H8/300 Floating point for H8/300 Machine directives for H8/300 Opcodes for H8/300 Options for H8/300 as has no additional command-line options for the Hitachi H8/300 family. Syntax for H8/300 The following documentation refers to the syntax for the Hitachi H8/300. Special characters for H8/300 ; is the line comment character. $ can be used instead of a newline to separate statements. Therefore you may not use $ in symbol names on the H8/300. Register names for H8/300 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. Addressing modes for H8/300 as understands the following addressing modes for the H8/300.   rn Register direct @rn Register indirect @(d, rn) @(d:16, rn) @(d:24, rn) Register indirect: 16-bit or 24-bit displacement, d, from register, n (24-bit displacements are only meaningful on the H8/300H) @rn+ Register indirect with post-increment @-rn Register indirect with pre-decrement @aa @aa:8 @aa:16 @aa:24 Absolute address, aa (the address size, :24, only makes sense on the H8/300H) #xx #xx:8 #xx:16 #xx:32 Immediate data, xx. Use the ‘:8’, ‘:16’, or ‘:32’ specifications for clarity, if you wish; but as neither requires this nor uses it—the data size required is taken from context. @@aa @@aa:8 Memory indirect. Use the ‘:8’ specification for clarity, if you wish; but as neither requires this nor uses it. Floating point for H8/300 The H8/300 family has no hardware floating point, but the .float directive generates IEEE floating-point numbers for compatibility with other development tools. Machine directives for H8/300 as has only one machine-dependent directive for the H8/300:   .h8300h Recognize and emit additional instructions for the H8/300H variant, and also make .int emit 32-bit numbers rather than the usual (16-bit) for the H8/300 family. For the H8/300 family (including the H8/300H), .word directives generate 16-bit numbers. Opcodes for H8/300 For detailed information on the H8/300 machine instruction set, see H8/300 Series Programming Manual (Hitachi ADE–602–025). For information specific to the H8/300H, see H8/300H Series Programming Manual (from Hitachi). as implements all the standard H8/300 opcodes. No additional pseudo-instructions are needed on this family. Four H8/300 instructions (add, cmp, mov, and  sub) are defined with variants using the suffixes, .b, .w, and .l to specify the size of a memory operand. as supports these suffixes, but does not require them; since one of the operands is always a register, as can deduce the correct size. For instance, since r0 refers to a 16-bit register, note the distinctions in the following examples. mov   r0,@foo mov   w r0,@foo If you use the size suffixes, as issues a warning when the suffix and the register size do not match. Top|Contents|Index|Previous|Next