AN2094 Freescale Semiconductor / Motorola, AN2094 Datasheet - Page 20

• Manufacturer Part Number: AN2094
• Description: ITU-T G.729 Implementation on StarCore SC140
• Manufacturer: Freescale Semiconductor / Motorola

Results
script that performs the analysis is presented in Appendix C. For stack size measurements, it is important to note
that the encoder and decoder do not run concurrently. Thus, the stack figure is the maximum of the individual stack
consumptions of the encoder and decoder.
3.2 Performance Estimation
The performance for the SC140 implementation of G.729 was estimated to be between 10 and 11.5 MCPS. This
estimate was based on G.729 implementations on mono ALU processors and a reported optimization factor of 2.4
for certain SC140 applications compared to mono ALU architectures [15]. Based on these estimations and our
particular implementation goals, a target value of 10.7 MCPS was chosen for our implementation. This is a worst-
case figure, based on the maximum processing time of both the encoder and decoder for one frame. The final
worst-case processor load was measured as 8.44 MCPS. It is important to note that different implementation goals
result in different performance targets than the one chosen. These results are summarized in Table 9.
3.3 Project Milestones
The following sections present the results of porting the G.729 code to the SC140. The primary performance data
(MCPS and program memory) is presented in comparison to the effort expended to achieve that performance. The
evolution of data size is also presented. The major milestones shown on all graphs include code versions after each
of the following steps:
3.4 Execution Time
The evolution in execution speed through the different versions of the project are summarized in Figure 4.
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Initial porting to the SC140 core, including multichannel transformations.
Project-level optimization, including inlining of DPF functions.
Initial function-level C optimization, before algorithmic changes.
The final C version, after algorithmic changes and reoptimization.
The final mixed implementation, including selected functions in assembly.
ITU-T G.729 Implementation on the StarCore™ SC140/SC1400 Cores, Rev. 1
Project Target
Results
Table 9. G.729 Implementation Target and Result
Worst-Case Processing Load (MCPS)
10.7
8.44
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