From 4df254f1f19d05a8172845f49930e8fbf9ef56be Mon Sep 17 00:00:00 2001 From: Måns Rullgård Date: Sun, 18 Oct 2009 18:51:54 +0000 Subject: WMAPRO: use some type punning in decode_coeffs() Originally committed as revision 20284 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/wmaprodec.c | 38 +++++++++++++++++++++++++------------- 1 file changed, 25 insertions(+), 13 deletions(-) (limited to 'libavcodec/wmaprodec.c') diff --git a/libavcodec/wmaprodec.c b/libavcodec/wmaprodec.c index 4d16c7f523..cbc97d9c82 100644 --- a/libavcodec/wmaprodec.c +++ b/libavcodec/wmaprodec.c @@ -762,6 +762,15 @@ static int decode_channel_transform(WMAProDecodeCtx* s) */ static int decode_coeffs(WMAProDecodeCtx *s, int c) { + /* Integers 0..15 as single-precision floats. The table saves a + costly int to float conversion, and storing the values as + integers allows fast sign-flipping. */ + static const int fval_tab[16] = { + 0x00000000, 0x3f800000, 0x40000000, 0x40400000, + 0x40800000, 0x40a00000, 0x40c00000, 0x40e00000, + 0x41000000, 0x41100000, 0x41200000, 0x41300000, + 0x41400000, 0x41500000, 0x41600000, 0x41700000, + }; int vlctable; VLC* vlc; WMAProChannelCtx* ci = &s->channel[c]; @@ -797,29 +806,32 @@ static int decode_coeffs(WMAProDecodeCtx *s, int c) for (i = 0; i < 4; i += 2) { idx = get_vlc2(&s->gb, vec2_vlc.table, VLCBITS, VEC2MAXDEPTH); if (idx == HUFF_VEC2_SIZE - 1) { - vals[i] = get_vlc2(&s->gb, vec1_vlc.table, VLCBITS, VEC1MAXDEPTH); - if (vals[i] == HUFF_VEC1_SIZE - 1) - vals[i] += ff_wma_get_large_val(&s->gb); - vals[i+1] = get_vlc2(&s->gb, vec1_vlc.table, VLCBITS, VEC1MAXDEPTH); - if (vals[i+1] == HUFF_VEC1_SIZE - 1) - vals[i+1] += ff_wma_get_large_val(&s->gb); + int v0, v1; + v0 = get_vlc2(&s->gb, vec1_vlc.table, VLCBITS, VEC1MAXDEPTH); + if (v0 == HUFF_VEC1_SIZE - 1) + v0 += ff_wma_get_large_val(&s->gb); + v1 = get_vlc2(&s->gb, vec1_vlc.table, VLCBITS, VEC1MAXDEPTH); + if (v1 == HUFF_VEC1_SIZE - 1) + v1 += ff_wma_get_large_val(&s->gb); + ((float*)vals)[i ] = v0; + ((float*)vals)[i+1] = v1; } else { - vals[i] = symbol_to_vec2[idx] >> 4; - vals[i+1] = symbol_to_vec2[idx] & 0xF; + vals[i] = fval_tab[symbol_to_vec2[idx] >> 4 ]; + vals[i+1] = fval_tab[symbol_to_vec2[idx] & 0xF]; } } } else { - vals[0] = symbol_to_vec4[idx] >> 12; - vals[1] = (symbol_to_vec4[idx] >> 8) & 0xF; - vals[2] = (symbol_to_vec4[idx] >> 4) & 0xF; - vals[3] = symbol_to_vec4[idx] & 0xF; + vals[0] = fval_tab[ symbol_to_vec4[idx] >> 12 ]; + vals[1] = fval_tab[(symbol_to_vec4[idx] >> 8) & 0xF]; + vals[2] = fval_tab[(symbol_to_vec4[idx] >> 4) & 0xF]; + vals[3] = fval_tab[ symbol_to_vec4[idx] & 0xF]; } /** decode sign */ for (i = 0; i < 4; i++) { if (vals[i]) { int sign = get_bits1(&s->gb) - 1; - ci->coeffs[cur_coeff] = (vals[i] ^ sign) - sign; + *(uint32_t*)&ci->coeffs[cur_coeff] = vals[i] ^ sign<<31; num_zeros = 0; } else { ci->coeffs[cur_coeff] = 0; -- cgit v1.2.3