Zilog ZUSBOPTS Bedienungsanleitung PDF herunterladen (Seite 353)

100

101

UM017105-0511 Program Configurations

Zilog Developer Studio II – ZNEO™

User Manual

325

Special Case: Partial Copy to RAM

A special case of this configuration is when you want to copy program code from just one

C source file into RAM, while retaining the rest of the code in EROM. This allows you to

investigate whether there might be power or speed savings to be realized by partitioning

your application in this way. Perform the following steps:

1. Select the

Distinct Code Segment for Each Module checkbox in the Advanced

page in the

Project Settings dialog box (see page 59) to direct the C-Compiler to

generate different code segment names for each file.

2. Add the linker commands to place the particular segment in RAM at run time and

EROM at load time.

For example, to copy the code for

main.c to RAM, add the following linker com-

mands in the

Additional Linker Directives dialog box (see Additional Directives –

see page 62):

change main_TEXT=RAM /* Run time main_TEXT is in RAM space */

copy main_TEXT EROM /* Load time main_TEXT is in EROM space */

define _low_main_copy = copy base of main_TEXT

define _low_main = base of main_TEXT

define _len_main = length of main_TEXT

3. The linker COPY directive only designates the load addresses and the run-time

addresses for the segment. The actual copying of the segment must be performed by

the start-up code. For example, if you are using the small model, copy and modify the

C startup provided in the installation under

src\boot\common\startupexs.asm,

rewriting the relevant section as follows:

;

; Copy main_TEXT into ERAM

;

LEA R0,_low_main_copy

LEA R1,_low_main

LD R2,#_len_main+1

JP mlab1

mlab0:

LD.B R3,(R0++)

LD.B (R1++),R3

mlab1:

DJNZ R2,mlab0

XREF _low_main_copy:EROM

XREF _len_main

XREF _low_main:RAM

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