sbc: ARM NEON optimization for scale factors calculation
Improves SBC encoding performance when joint stereo is not used.
Benchmarked on ARM Cortex-A8:
== Before: ==
$ time ./sbcenc -b53 -s8 test.au > /dev/null
real 0m4.756s
user 0m4.313s
sys 0m0.438s
samples % image name symbol name
2569 27.6296 sbcenc sbc_pack_frame
1934 20.8002 sbcenc sbc_analyze_4b_8s_neon
1386 14.9064 sbcenc sbc_calculate_bits
1221 13.1319 sbcenc sbc_calc_scalefactors
996 10.7120 sbcenc sbc_enc_process_input_8s_be
878 9.4429 no-vmlinux /no-vmlinux
204 2.1940 sbcenc sbc_encode
56 0.6023 libc-2.10.1.so memcpy
== After: ==
$ time ./sbcenc -b53 -s8 test.au > /dev/null
real 0m4.220s
user 0m3.797s
sys 0m0.422s
samples % image name symbol name
2563 31.3249 sbcenc sbc_pack_frame
1892 23.1239 sbcenc sbc_analyze_4b_8s_neon
1368 16.7196 sbcenc sbc_calculate_bits
961 11.7453 sbcenc sbc_enc_process_input_8s_be
836 10.2176 no-vmlinux /no-vmlinux
262 3.2022 sbcenc sbc_calc_scalefactors_neon
199 2.4322 sbcenc sbc_encode
49 0.5989 libc-2.10.1.so memcpy
2 files changed
