Compression solution for embedded devices and systems
An embedded device is hibernated by storing state data of the embedded device to a non-volatile data storage medium, and powering off the embedded device. The embedded device is later woken up in response to the detection of a wakeup event. The state data stored in the RAM of the embedded device comprises one or more registers of a Central Processing Unit (CPU) of the embedded device, one or more registers of a system-on-chip (SOC) of the embedded device, and the system and applications code and data. Waking the embedded device comprises loading, from the non-volatile data storage medium, initial memory sections that are used to run a kernel of the embedded device. State data that is stored in the RAM of a system is compressed by dividing the RAM into a plurality of sections and independently choosing, for each section in the plurality of sections, a compression arithmetic.
1. A method, comprising:
maintaining data needed for satellite positioning navigation in a set of volatile memory locations on a device;
compressing data in volatile memory of the device, including:
copying the data from the set of volatile memory locations to a separate RAM on the device;
after copying, dividing the RAM into a plurality of sections;
for each section in the plurality of sections, performing the steps of:
selecting a first compression arithmetic;
generating a set of compression data, the set of compression data comprising data in the each section compressed using the first compression arithmetic;
in response to determining that the set of compressed data does not meet a compression-ratio requirement, performing the steps of:
selecting a second compression arithmetic; and
regenerating the set of compression data, the set of compression data comprising data in the each section compressed using the second compression arithmetic; and
storing the set of compressed data to a non-volatile data storage medium.
2. The method of claim 1 , wherein compressing further includes storing information that indicates an association between a compression arithmetic used to generate the set of compressed data and the each section.
3. The method of claim 1 , wherein the first compression arithmetic has a higher decompression speed than the second compression arithmetic.
4. The method of claim 1 , wherein compressing the data is performed in response to a hibernation event.
5. The method of claim 4 , wherein the hibernation event includes powering off the device.
6. The method of claim 1 , further comprising, before generating the set of compressed data, copying a tiny kernel to the RAM.
7. The method of claim 1 , further comprising, before compressing, maintaining operating system code and data for the device in the RAM.
8. The method of claim 1 , further comprising, before compressing, maintaining application code and data for the device in the RAM.
9. The method of claim 1 , wherein the set of volatile memory locations includes registers in a satellite positioning chipset of the device.
10. The method of claim 1 , wherein the set of volatile memory locations includes on-chip memory in a GPS chipset of the device.
11. The method of claim 1 , further comprising, before compressing, suspending peripheral components of the device.
12. The method of claim 1 , wherein the peripheral components include one or more of an LCD display, a touch panel, and an audio player.
13. The method of claim 1 , further comprising:
waking the device, wherein waking the device comprises:
for each section in the plurality of sections, performing the steps of:
selecting, based on information that indicates an association between the compression arithmetic used to generate the set of compressed data for the each section, a decompression arithmetic; and
decompressing the set of compressed data for the each section using the decompression arithmetic.
14. The method of claim 6 , further comprising:
waking the device, wherein waking the device comprises loading the tiny kernel to the RAM.
15. The method of claim 14 , further comprising, after loading the tiny kernel:
for each section in the plurality of sections, performing the steps of:
selecting, based on information that indicates an association between the compression arithmetic used to generate the set of compressed data for the each section, a decompression arithmetic; and
decompressing the set of compressed data for the each section using the decompression arithmetic.
16. The method of claim 14 , further comprising, after decompressing each section, loading a display framebuffer section of the device.
17. The method of claim 1 , wherein the RAM is an SDRAM.
18. The method of claim 1 , wherein the non-volatile storage is one of: a hard drive, an SD card, an MMC memory, and a flash memory.
19. An embedded device comprising a RAM and a non-volatile data storage medium, the embedded device further comprising:
a set of volatile memory locations that maintain data needed for satellite positioning navigation;
a hibernation program, the hibernation program performing a method of compressing data in volatile memory of the device, including:
copying the data from the set of volatile memory locations to a separate RAM on the device;
after copying, dividing the RAM into a plurality of sections;
for each section in the plurality of sections, performing the steps of:
selecting a first compression arithmetic;
generating a set of compression data, the set of compression data comprising data in the each section compressed using the first compression arithmetic;
in response to determining that the set of compressed data does not meet a compression-ratio requirement, performing the steps of:
selecting a second compression arithmetic; and
regenerating the set of compression data, the set of compression data comprising data in the each section compressed using the second compression arithmetic; and
storing the set of compressed data to a non-volatile data storage medium.
20. The embedded device of claim 19 , wherein the embedded device comprises a GPS receiver.