Lattice LatticeMico8, Руководство пользователя

Страница: 19 / 23

19
LatticeMico 8 Microcontroller
Lattice Semiconductor User’s Guide
• Octal values : Octal values must be prefixed with the numeric character ‘0’. (e.g. 077, 066, and 012 are valid
octal constants).
• Character constants : Single character constants must be enclosed in single quotation marks. (e.g. ‘A’, ‘v’, ‘9’
are all valid character constants).
• Decimal constants : Any sequence of decimal numbers can be a valid constant. (e.g. 123, 255, 231 are valid
decimal constants).
• Location counter : The special character $ (dollar sign) is used to give the current value of the location counter.
Note: The hexadecimal, octal, and decimal constants can be optionally prefixed with a ‘+’ or ‘-’ sign.
Assembler Directives
In addition to the instructions described in the Instruction Set section, the Assembler also supports the following
directives. An Assembler directive must be prefixed with a ‘.’ character.
• .org : This directive allows code to be placed at specific addresses. The syntax for this directive is:
.org <constant>
The constant can be of any form described in the previous section. The Assembler will terminate with an error, if
the .org directive is given a location which is less than the current “local counter” value.
• .equ : This directive can be used to assign symbolic names to constants. The syntax of the directive is:
.equ <symbolic name>,<constant>
.equ newline,’\n’
...
movi r2,newline
• .data : This directive can be used to embed arbitrary data in the assembler. The syntax for this directive is:
.data <constant>
The following figure is an example of the listing generated by the Assembler:
Figure 4. Example of Assembler Generated Listing
Loc Opcode Opcode
Counter (Hex) (Bin)
0x0000 0x33001 110011000000000001 b start
0x0001 start:
0x0001 0x10000 010000000000000000 nop
0x0002 add:
0x0002 0x12055 010010000001010101 movi R00,0x55
0x0003 0x12105 010010000100000101 movi R01,0x05
0x0004 0x12203 010010001000000011 movi R02,0x03
0x0005 0x08110 001000000100010000 add R01,R02
0x0006 0x0A101 001010000100000001 addi R01,0x01
0x0007 0x10308 010000001100001000 mov R03,R01
0x0008 0x10410 010000010000010000 mov R04,R02
0x0009 0x12535 010010010100110101 movi R05,0x35
0x000A 0x12643 010010011001000011 movi R06,0x43
0x000B 0x08628 001000011000101000 add R06,R05
0x000C 0x0A613 001010011000010011 addi R06,0x13
0x000D 0x10728 010000011100101000 mov R07,R05
•
•
•