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S12CPUV2 Reference Manual, Rev. 4.0

Freescale Semiconductor

6.5 Source Forms

The glossary pages provide only essential information about assembler

source forms. Assemblers generally support a number of assembler

directives, allow definition of program labels, and have special conventions

for comments. For complete information about writing source files for a

particular assembler, refer to the documentation provided by the assembler

vendor.

Assemblers are typically flexible about the use of spaces and tabs. Often,

any number of spaces or tabs can be used where a single space is shown

on the glossary pages. Spaces and tabs are also normally allowed before

and after commas. When program labels are used, there must also be at

least one tab or space before all instruction mnemonics. This required

space is not apparent in the source forms.

Everything in the source forms columns, except expressions in italic

characters, is literal information which must appear in the assembly source

file exactly as shown. The initial 3- to 5-letter mnemonic is always a literal

expression. All commas, pound signs (#), parentheses, square brackets ( [

or ] ), plus signs (+), minus signs (–), and the register designation D (as in

[D,... ), are literal characters.

Groups of italic characters in the columns represent variable information to

be supplied by the programmer. These groups can include any

alphanumeric character or the underscore character, but cannot include a

space or comma. For example, the groups xysp and oprx0_xysp are both

valid, but the two groups oprx0 xysp are not valid because there is a space

between them. Permitted syntax is described here.

The definition of a legal label or expression varies from assembler to

assembler. Assemblers also vary in the way CPU registers are specified.

Refer to assembler documentation for detailed information. Recommended

PC.

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