MSC100ABIRM Motorola / Freescale Semiconductor, MSC100ABIRM Datasheet - Page 80

• Manufacturer Part Number: MSC100ABIRM
• Description: SC100 Application Binary Interface Reference Manual
• Manufacturer: Motorola / Freescale Semiconductor

Assembler Syntax and Directives
6.2.6.4 Source Statement Format
Each source statement may include several fields (for a single instruction assembly line) separated by one
or more spaces or tabs: a label field, an operation field, an operand field or data transfer fields, and a
comment field. Only fields preceding the comment field are considered significant to the assembler; the
comment field is ignored. Opcode, directives, or pseudo ops may not begin in column 1 (first character
location). Labels must begin in column 1 unless followed by a colon, as shown in Example 6-1.
Example 6-1. Column 1 Labels
lab
SC140 allows instruction groupings in which multiple instructions are executed in parallel. Instruction
groups are delimited with []. An instruction group may not begin in column 1. An instruction group may
span multiple lines without the use of a continuation character, as shown in Example 6-2.
Example 6-2. Multiple-Line Instruction Group
6.2.6.5 Labels
The label field is the first field of a source statement. A space or tab as the first character on a line
ordinarily indicates that the label field is empty. Labels are subject to the following rules:
6.2.6.6 Operation Field
The operation field appears after the label field, and must be preceded by at least one space or tab. Entries
in the operation field may be one of three types:
Opcode
Directive
Macro call
6-6
•
•
•
•
•
The first character of a label is an alphabetic character.
A label that has an underscore (_) as the first character is a global label.
Labels may be indented if the label symbol is immediately followed by a colon (:) with no
intervening spaces. In this case, all characters preceding the label on the line must be whitespace
characters—spaces or tabs.
A label may occur only once in the label field of an individual source file unless it is used as a local
label, a label local to a section, or is used with the SET directive. If a non-local label occurs more
than once in a label field, each reference to that label after the first will be flagged as an error.
A line consisting only of a label only is valid and has the effect of assigning the value of the location
counter to the label. With the exception of some directives, a label is assigned the value of the
location counter of the first word of the instruction or data being assembled.
[
]
move.2w (r0),d0d1
move.w (sp-14),r2
clr d5
Mnemonics that correspond directly to DSP machine instructions.
Special operation codes known to the assembler which control the assembly
process.
Invocation of a previously defined macro which is to be inserted in place of the
macro call.
Preliminary (April 2000)
clr d6 clr d7
; Two word memory to register move
SC100 Application Binary Interface
clr d4