UM0144 datasheet(22/92 Pages) STMICROELECTRONICS

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3 ST7 Assembler

ST7 Assembler Linker

22/92

UM0144

Don't worry if some directives don't make sense yet; they will be covered soon. Also, take

special notice of the SEGMENT directive.

3.4

Segmentation

Segments are very important. You have to understand segments before you can use the

assembler. Take the time to understand them now and you'll save yourself a lot of puzzling

later.

Segmentation is a way of 'naming' areas of your code and making sure that the linker collates

areas of the same name together in the same memory area, whatever the order of the

segments in the object files. Up to 128 different segments may be defined in each module.

The segment directive itself has four arguments, separated by spaces:

[<name>]

SEGMENT [<align>] [<combine>] '<class>' [cod]

For example:

segment word at: FFFC 'code'

WORD start

end

FILE1:

st7/

BYTES

segment byte at: 80-FF ‘RAM0’

counter.b

ds.b

; loop counter

address.b

ds.w

; address storage

ds.b 15

; stack allocation

stack

ds.b

; stack grows downward

segment byte at: E000-FFFF ‘eprom’

ld A,#stack

ld S,A

; init stack pointer

end

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