Zilog ZUSBOPTS User Manual
Page 348
Program Configurations
UM017105-0511
320
Zilog Developer Studio II – ZNEO™
User Manual
1. To set up this configuration, you must place the CODE segment in ERAM at run time
and EROM at load time. Do this by adding the following linker commands in the
Additional Linker Directives
dialog box (see
change code=ERAM /* Run time CODE is in ERAM space */
copy code EROM /* Load time CODE is in EROM space */
define _low_code_copy = copy base of CODE
define _low_code = base of CODE
define _len_code = length of CODE
2. 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 CODE into ERAM
;
LEA
R0,_low_code_copy
LEA
R1,_low_code
LD
R2,#_len_code+1
JP
clab1
clab0:
LD.B
R3,(R0++)
LD.B
(R1++),R3
clab1:
DJNZ
R2,clab0
XREF
_low_code_copy:EROM
XREF
_len_code:ERAM
XREF
_low_code:ERAM
3. Finally, add your modified start-up module to your project. Select the
Included in
Project
button in the
Objects and Libraries
page of the
Project Settings
dialog box
– see page 66) and also add the modified source code file to
your project using the Add Files command from the
Project
menu.
Special Case: Partial Copy to ERAM
A special case of this configuration is when you want to copy program code from just one
C source file into ERAM, while retaining the rest of the code in EROM. This allows you
to gain the potential speed advantages of external RAM over external Flash for a specific
module. 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