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PRELIMINARY
JPEG CODEC
S3C6400X RISC MICROPROCESSOR
22-4
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
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Figure 22-2. Access Order in Quantizer Table
INTERRUPT SIGNAL
Interrupt signal will be generated under the following conditions (the register,
JPGIRQ
, which identifies causes)
1. Compression or decompression process for one frame is completed,
2.
JPGIRQ[3]
is set high during decompression when the registers storing the image size and sampling
factor are ready to be read out after the marker analysis.
For interrupt 1, the normal process is finished. To clear the pending interrupt request, read the
JPGSTS
register. If there no encoding or decoding error,
JPGIRQ
will be read as 0x40.
Canceling the interrupt 2 is also done by reading
JPGIRQ
. If there is no header parsing error, it will be read as
0x08. The interrupt 2 indicates that the decompression process is paused.
3-interrupt signals are used to distinguish interrupt occurred circumstance.
INTERRUPT SETTING REGISTER
This register sets whether the interrupt is allowed or not, when it is ready to decompress an image. To allow the
interrupt, set
JPGIRQS
[3] to high, before starting the decompression process. When this interrupt occurs, JPEG
codec pauses the process and drives
JPGSTS
[0] high as it is. Cancellation of the interrupt by this register setting
is done by reading
JPGIRQ
MARKER PROCESS
The following markers are generated during compression.