AN2121 Freescale Semiconductor / Motorola, AN2121 Datasheet - Page 26

• Manufacturer Part Number: AN2121
• Description: JPEG2000 Arithmetic Encoding on StarCore SC140
• Manufacturer: Freescale Semiconductor / Motorola

Implementation
In Code Example 6, if the T bit is set, d7 is transferred to d0; otherwise d7 is added to d1.
3.2.4
Table 4 compares the results for the optimized assembler version of the arithmetic coder with the results
for the C version for both a typical image and a constant grey scale image. The time required for a 1M
pixel color image in assembler was derived by extrapolating the results obtained with a single 128
grey scale tile, as it was done for C code.
The optimized assembler completes the task in less than a third of the time required by the C code. For the
constant grey scale image, the assembler version is about 17 times faster than the C version run on the
DSP56307 with in-line optimized assembler functions (see Section 3.1.3). Note that this result assumes
that the DSP56307 runs at 100 MHz while StarCore operates at 300 MHz.
22
Table 4. Comparison of Results for Assembly with C Versions of Arithmetic Encoder
Typical image
Constant grey
scale
Results
tfrt
Image
JPEG2000 Arithmetic Encoding on the StarCore SC140
d7,d0
Freescale Semiconductor, Inc.
Code Example 6. T Bit Selects an Instruction
For More Information On This Product,
Clock Cycles
(128
1.5 M
9586
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128)
Assembly
iff
(1 Megapixel, Color)
Time (ms)
add d7,d1,d1
640
4
(1 Megapixel, Color)
Time (ms)
C Code
1960
14
128