The official git repository for OSD-Contiki, the open source OS for the Internet of Things
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Benoît Thébaudeau 37e73894f1 cc2538: Move SoC data to a dedicated section to save space
Some SoC data requires huge alignments. E.g., the µDMA channel control table has
to be 1024-byte aligned. This table was simply aligned to 1024 bytes in the C
code, which had the following consequences, wasting a lot of RAM:
 - As this table could be placed anywhere in .bss, there could be an alignment
   gap of up to 1023 bytes between the preceding data and this table.
 - The size of this table was also aligned to 1024 bytes, regardless of
   UDMA_CONF_MAX_CHANNEL, making this configuration option supposed to save RAM
   just useless.
 - .bss was also aligned to at least 1024 bytes, creating a huge alignment gap
   between .data and .bss.

Instead of relying on the compiler to force this alignment, and on the linker to
automatically place data, this change places carefully such SoC data in RAM
using the linker script. A dedicated section is created to place such SoC data
requiring huge alignments, and it is put at the beginning of the SRAM in order
to ensure a maximal alignment without any gap. In this way, the alignment of
.bss also remains normal, and the size of this table is not constrained by its
alignment, but only by its contents (i.e. by UDMA_CONF_MAX_CHANNEL).

In the case of the µDMA channel control table, the data is still zeroed by
udma_init() (instead of also being zeroed as part of .bss).

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
2013-12-23 15:06:13 +01:00
apps Bumped the version number from 2.6 to 3.x, which is to be used in the development branch 2013-12-12 17:33:18 +01:00
core Bumped the version number from 2.6 to 3.x, which is to be used in the development branch 2013-12-12 17:33:18 +01:00
cpu cc2538: Move SoC data to a dedicated section to save space 2013-12-23 15:06:13 +01:00
doc Bumped the version number from 2.6 to 3.x, which is to be used in the development branch 2013-12-12 17:33:18 +01:00
examples Merge pull request #140 from cetic/slip-radio-platforms 2013-12-02 09:23:10 -08:00
platform Merge remote-tracking branch 'upstream/master' 2013-12-12 20:46:43 +01:00
regression-tests Travis test for slip-radio 2013-12-09 21:06:37 +01:00
tools Have CBM DOS filetype of imported files match the one used by cc65. 2013-12-12 18:57:40 +01:00
.gitignore Adjustments for the switch from 'atari' to 'atarixl'. 2013-10-03 23:54:33 +02:00
.gitmodules Added mspsim as a submodule instead of as a binary mspsim.jar file 2013-11-07 17:28:50 +01:00
.travis.yml Travis test for slip-radio 2013-12-09 21:06:37 +01:00
LICENSE Removed the explicit year 2012 to make it more generic 2012-10-25 23:08:54 +02:00
Makefile.include Merge pull request #474 from adamdunkels/push/cleanup-vnc 2013-11-29 05:07:53 -08:00
README-BUILDING.md Rename to md 2013-03-26 23:15:37 +01:00
README-EXAMPLES.md Several minor consistency improvements. 2013-07-31 00:55:31 +02:00
README.md Rename to md 2013-03-26 23:15:37 +01:00

The Contiki Operating System

Build Status

Contiki is an open source operating system that runs on tiny low-power microcontrollers and makes it possible to develop applications that make efficient use of the hardware while providing standardized low-power wireless communication for a range of hardware platforms.

Contiki is used in numerous commercial and non-commercial systems, such as city sound monitoring, street lights, networked electrical power meters, industrial monitoring, radiation monitoring, construction site monitoring, alarm systems, remote house monitoring, and so on.

For more information, see the Contiki website:

http://contiki-os.org