UM0144 datasheet(53/92 Pages) STMICROELECTRONICS

номер детали	UM0144

подробное описание детали	ST7 Assembler Linker

PDF	92 Pages

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производитель	STMICROELECTRONICS [STMicroelectronics]

домашняя страница	http://www.st.com

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ST7 Assembler Linker

UM0144

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A.12

DS.B

Purpose:

Define byte space in object code.

Format:

DS.B [optional number of bytes]

Description:

This directive is used to 'space out' label definitions. For example let's say we need a

set of byte-sized temporary storage locations to be defined in RAM, starting at

address $4000. We could write:

segment byte at 4000 'RAM'

temp1

equ $4000

temp2

equ $4001

which would work fine, however, we recommend you to write:

segment byte at 4000 'RAM'

temp1

DS.B

temp2

DS.B

which does the same job. The advantage is that the PC increments automatically.

There are two other types of DS instructions available for doing WORD and LONG

length storage areas: DS.W and DS.L. Note that the areas in question are not initial-

ized to any value; it's merely a way of allocating values to labels.

The optional argument specifies how many bytes to allocate; the default is 1.

Because no code is generated to fill the space, you are not allowed to use DS.B in

segments containing code, only for segments with data definitions.

Example:

UM0144 датащи(PDF) 53 Page - STMicroelectronics