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After the division routines the entropy decoder was the largest part of Monkey's Audio at the fast levels, with two things to gain. All of its state, the range coder's and the Rice parameters, was in statics, so each use was a load and each update a store: about half of the function's time on ARM7TDMI, where a load is 3 cycles. Copy it to locals for the length of a block and write it back after. The functions that take a pointer to it have to be inlined for that to work, and on ARMv4 gcc left the per-sample one out of line, so force them. The symbol was found by dividing low by help and searching the count table for the quotient. counts[n] <= low / help is the same as counts[n] * help <= low, so search with the multiply instead: the first symbols are by far the likeliest. That leaves two divisions a sample from three. MHz for real time in perfsim's models, -c1000, -c2000 and -c3000: Clip+ (ARMv5) 37.9, 53.8, 81.8 to 32.5, 48.4, 76.4 e200 (ARMv4) 45.3, 68.6, 111.4 to 35.2, 58.5, 101.3 A Clip+ measures 32.85 at -c1000 (61.4 before this and the division change), with test_codec's checksum, 1008ffab, the same as the old code's. The standalone decoder gives identical output for all four levels tested. The path for files older than 3.98 has the same change and was not tested, for want of a file. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Change-Id: Idf9002a5b5f3a423f44f70443936ea5ac427cd12 |
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| arm_support | ||
| fixedpoint | ||
| libsetjmp | ||
| microtar | ||
| mipsunwinder | ||
| rbcodec | ||
| skin_parser | ||
| tlsf | ||
| unwarminder | ||
| utf8proc | ||