Files
system76-coreboot/payloads/libpayload
Julius Werner 96b00a50f1 libpayload: Add simple 32.32 fixed-point math API
struct fraction is slooooooooooow. This patch adds a simple 64-bit
(32-bits integral, 32-bits fractional) fixed-point math API that is
*much* faster (observed roughly 5x speed-up) when doing intensive
graphics operations. It is optimized for speed over accuracy so some
operations may lose a bit more precision than expected, but overall it's
still plenty of bits for most use cases.

Also includes support for basic trigonometric functions with a small
lookup table.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: Id0f9c23980e36ce0ac0b7c5cd0bc66153bca1fd0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/42993
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
2020-07-09 00:32:11 +00:00
..
2020-03-02 15:03:03 +00:00
2015-06-08 00:55:07 +02:00

-------------------------------------------------------------------------------
libpayload README
-------------------------------------------------------------------------------

libpayload is a minimal library to support standalone payloads
that can be booted with firmware like coreboot. It handles the setup
code, and provides common C library symbols such as malloc() and printf().

Note: This is _not_ a standard library for use with an operating system,
rather it's only useful for coreboot payload development!
See https://www.coreboot.org for details on coreboot.


Installation
------------

 $ git clone https://review.coreboot.org/coreboot.git

 $ cd coreboot/payloads/libpayload

 $ make menuconfig

 $ make

 $ make install (optional, will install into ./install per default)

On x86 systems, libpayload will always be 32-bit even if your host OS runs
in 64-bit, so you might have to install the 32-bit libgcc version.
On Debian systems you'd do 'apt-get install gcc-multilib' for example.

Run 'make distclean' before switching boards. This command will remove
your current .config file, so you need 'make menuconfig' again or
'make defconfig' in order to set up configuration. Default configuration
is based on 'configs/defconfig'. See the configs/ directory for examples
of configuration.


Usage
-----

Here's an example of a very simple payload (hello.c) and how to build it:

 #include <libpayload.h>

 int main(void)
 {
     printf("Hello, world!\n");
     return 0;
 }

Building the payload using the 'lpgcc' compiler wrapper:

 $ lpgcc -o hello.elf hello.c

Please see the sample/ directory for details.


Website and Mailing List
------------------------

The main website is https://www.coreboot.org/Libpayload.

For additional information, patches, and discussions, please join the
coreboot mailing list at https://www.coreboot.org/Mailinglist, where most
libpayload developers are subscribed.


Copyright and License
---------------------

See LICENSES.