Use a table for PVQ encoding/decoding.

58.4% speedup (2.4x faster) on test_unit_cwrs32 (no custom modes).
Gives a 3.2% speedup on
 ./opus_demo restricted-lowdelay 48000 2 96000 comp48-stereo.sw /dev/null
 on a 600 MHz Cortex A8.

1 files changed, 308 insertions, 301 deletions

diff --git a/celt/cwrs.c b/celt/cwrs.c
index 8edc919d..e6a25e92 100644
--- a/celt/cwrs.c
+++ b/celt/cwrs.c
@@ -71,64 +71,6 @@ int log2_frac(opus_uint32 val, int frac)
 }
 #endif
 
-#ifndef SMALL_FOOTPRINT
-
-#define MASK32 (0xFFFFFFFF)
-
-/*INV_TABLE[i] holds the multiplicative inverse of (2*i+1) mod 2**32.*/
-static const opus_uint32 INV_TABLE[53]={
-  0x00000001,0xAAAAAAAB,0xCCCCCCCD,0xB6DB6DB7,
-  0x38E38E39,0xBA2E8BA3,0xC4EC4EC5,0xEEEEEEEF,
-  0xF0F0F0F1,0x286BCA1B,0x3CF3CF3D,0xE9BD37A7,
-  0xC28F5C29,0x684BDA13,0x4F72C235,0xBDEF7BDF,
-  0x3E0F83E1,0x8AF8AF8B,0x914C1BAD,0x96F96F97,
-  0xC18F9C19,0x2FA0BE83,0xA4FA4FA5,0x677D46CF,
-  0x1A1F58D1,0xFAFAFAFB,0x8C13521D,0x586FB587,
-  0xB823EE09,0xA08AD8F3,0xC10C9715,0xBEFBEFBF,
-  0xC0FC0FC1,0x07A44C6B,0xA33F128D,0xE327A977,
-  0xC7E3F1F9,0x962FC963,0x3F2B3885,0x613716AF,
-  0x781948B1,0x2B2E43DB,0xFCFCFCFD,0x6FD0EB67,
-  0xFA3F47E9,0xD2FD2FD3,0x3F4FD3F5,0xD4E25B9F,
-  0x5F02A3A1,0xBF5A814B,0x7C32B16D,0xD3431B57,
-  0xD8FD8FD9,
-};
-
-/*Computes (_a*_b-_c)/(2*_d+1) when the quotient is known to be exact.
-  _a, _b, _c, and _d may be arbitrary so long as the arbitrary precision result
-   fits in 32 bits, but currently the table for multiplicative inverses is only
-   valid for _d<=52.*/
-static inline opus_uint32 imusdiv32odd(opus_uint32 _a,opus_uint32 _b,
- opus_uint32 _c,int _d){
-  celt_assert(_d<=52);
-  return (_a*_b-_c)*INV_TABLE[_d]&MASK32;
-}
-
-/*Computes (_a*_b-_c)/_d when the quotient is known to be exact.
-  _d does not actually have to be even, but imusdiv32odd will be faster when
-   it's odd, so you should use that instead.
-  _a and _d are assumed to be small (e.g., _a*_d fits in 32 bits; currently the
-   table for multiplicative inverses is only valid for _d<=54).
-  _b and _c may be arbitrary so long as the arbitrary precision reuslt fits in
-   32 bits.*/
-static inline opus_uint32 imusdiv32even(opus_uint32 _a,opus_uint32 _b,
- opus_uint32 _c,int _d){
-  opus_uint32 inv;
-  int           mask;
-  int           shift;
-  int           one;
-  celt_assert(_d>0);
-  celt_assert(_d<=54);
-  shift=EC_ILOG(_d^(_d-1));
-  inv=INV_TABLE[(_d-1)>>shift];
-  shift--;
-  one=1<<shift;
-  mask=one-1;
-  return (_a*(_b>>shift)-(_c>>shift)+
-   ((_a*(_b&mask)+one-(_c&mask))>>shift)-1)*inv&MASK32;
-}
-
-#endif /* SMALL_FOOTPRINT */
-
 /*Although derived separately, the pulse vector coding scheme is equivalent to
    a Pyramid Vector Quantizer \cite{Fis86}.
   Some additional notes about an early version appear at
@@ -248,46 +190,301 @@ static inline opus_uint32 imusdiv32even(opus_uint32 _a,opus_uint32 _b,
     year=1986
   }*/
 
-#ifndef SMALL_FOOTPRINT
-/*Compute U(2,_k).
-  Note that this may be called with _k=32768 (maxK[2]+1).*/
-static inline unsigned ucwrs2(unsigned _k){
-  celt_assert(_k>0);
-  return _k+(_k-1);
-}
+#if !defined(SMALL_FOOTPRINT)
+
+/*U(N,K) = U(K,N) := N>0?K>0?U(N-1,K)+U(N,K-1)+U(N-1,K-1):0:K>0?1:0*/
+# define CELT_PVQ_U(_n,_k) (CELT_PVQ_U_ROW[IMIN(_n,_k)][IMAX(_n,_k)])
+/*V(N,K) := U(N,K)+U(N,K+1) = the number of PVQ codewords for a band of size N
+   with K pulses allocated to it.*/
+# define CELT_PVQ_V(_n,_k) (CELT_PVQ_U(_n,_k)+CELT_PVQ_U(_n,(_k)+1))
+
+/*For each V(N,K) supported, we will access element U(min(N,K+1),max(N,K+1)).
+  Thus, the number of entries in row I is the larger of the maximum number of
+   pulses we will ever allocate for a given N=I (K=128, or however many fit in
+   32 bits, whichever is smaller), plus one, and the maximum N for which
+   K=I-1 pulses fit in 32 bits.
+  The largest band size in an Opus Custom mode is 208.
+  Otherwise, we can limit things to the set of N which can be achieved by
+   splitting a band from a standard Opus mode: 176, 144, 96, 88, 72, 64, 48,
+   44, 36, 32, 24, 22, 18, 16, 8, 4, 2).*/
+#if defined(CUSTOM_MODES)
+static const opus_uint32 CELT_PVQ_U_DATA[1488]={
+#else
+static const opus_uint32 CELT_PVQ_U_DATA[1272]={
+#endif
+  /*N=0, K=0...176:*/
+  1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+#if defined(CUSTOM_MODES)
+  /*...208:*/
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0,
+#endif
+  /*N=1, K=1...176:*/
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+#if defined(CUSTOM_MODES)
+  /*...208:*/
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1,
+#endif
+  /*N=2, K=2...176:*/
+  3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41,
+  43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79,
+  81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113,
+  115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 139, 141, 143,
+  145, 147, 149, 151, 153, 155, 157, 159, 161, 163, 165, 167, 169, 171, 173,
+  175, 177, 179, 181, 183, 185, 187, 189, 191, 193, 195, 197, 199, 201, 203,
+  205, 207, 209, 211, 213, 215, 217, 219, 221, 223, 225, 227, 229, 231, 233,
+  235, 237, 239, 241, 243, 245, 247, 249, 251, 253, 255, 257, 259, 261, 263,
+  265, 267, 269, 271, 273, 275, 277, 279, 281, 283, 285, 287, 289, 291, 293,
+  295, 297, 299, 301, 303, 305, 307, 309, 311, 313, 315, 317, 319, 321, 323,
+  325, 327, 329, 331, 333, 335, 337, 339, 341, 343, 345, 347, 349, 351,
+#if defined(CUSTOM_MODES)
+  /*...208:*/
+  353, 355, 357, 359, 361, 363, 365, 367, 369, 371, 373, 375, 377, 379, 381,
+  383, 385, 387, 389, 391, 393, 395, 397, 399, 401, 403, 405, 407, 409, 411,
+  413, 415,
+#endif
+  /*N=3, K=3...176:*/
+  13, 25, 41, 61, 85, 113, 145, 181, 221, 265, 313, 365, 421, 481, 545, 613,
+  685, 761, 841, 925, 1013, 1105, 1201, 1301, 1405, 1513, 1625, 1741, 1861,
+  1985, 2113, 2245, 2381, 2521, 2665, 2813, 2965, 3121, 3281, 3445, 3613, 3785,
+  3961, 4141, 4325, 4513, 4705, 4901, 5101, 5305, 5513, 5725, 5941, 6161, 6385,
+  6613, 6845, 7081, 7321, 7565, 7813, 8065, 8321, 8581, 8845, 9113, 9385, 9661,
+  9941, 10225, 10513, 10805, 11101, 11401, 11705, 12013, 12325, 12641, 12961,
+  13285, 13613, 13945, 14281, 14621, 14965, 15313, 15665, 16021, 16381, 16745,
+  17113, 17485, 17861, 18241, 18625, 19013, 19405, 19801, 20201, 20605, 21013,
+  21425, 21841, 22261, 22685, 23113, 23545, 23981, 24421, 24865, 25313, 25765,
+  26221, 26681, 27145, 27613, 28085, 28561, 29041, 29525, 30013, 30505, 31001,
+  31501, 32005, 32513, 33025, 33541, 34061, 34585, 35113, 35645, 36181, 36721,
+  37265, 37813, 38365, 38921, 39481, 40045, 40613, 41185, 41761, 42341, 42925,
+  43513, 44105, 44701, 45301, 45905, 46513, 47125, 47741, 48361, 48985, 49613,
+  50245, 50881, 51521, 52165, 52813, 53465, 54121, 54781, 55445, 56113, 56785,
+  57461, 58141, 58825, 59513, 60205, 60901, 61601,
+#if defined(CUSTOM_MODES)
+  /*...208:*/
+  62305, 63013, 63725, 64441, 65161, 65885, 66613, 67345, 68081, 68821, 69565,
+  70313, 71065, 71821, 72581, 73345, 74113, 74885, 75661, 76441, 77225, 78013,
+  78805, 79601, 80401, 81205, 82013, 82825, 83641, 84461, 85285, 86113,
+#endif
+  /*N=4, K=4...176:*/
+  63, 129, 231, 377, 575, 833, 1159, 1561, 2047, 2625, 3303, 4089, 4991, 6017,
+  7175, 8473, 9919, 11521, 13287, 15225, 17343, 19649, 22151, 24857, 27775,
+  30913, 34279, 37881, 41727, 45825, 50183, 54809, 59711, 64897, 70375, 76153,
+  82239, 88641, 95367, 102425, 109823, 117569, 125671, 134137, 142975, 152193,
+  161799, 171801, 182207, 193025, 204263, 215929, 228031, 240577, 253575,
+  267033, 280959, 295361, 310247, 325625, 341503, 357889, 374791, 392217,
+  410175, 428673, 447719, 467321, 487487, 508225, 529543, 551449, 573951,
+  597057, 620775, 645113, 670079, 695681, 721927, 748825, 776383, 804609,
+  833511, 863097, 893375, 924353, 956039, 988441, 1021567, 1055425, 1090023,
+  1125369, 1161471, 1198337, 1235975, 1274393, 1313599, 1353601, 1394407,
+  1436025, 1478463, 1521729, 1565831, 1610777, 1656575, 1703233, 1750759,
+  1799161, 1848447, 1898625, 1949703, 2001689, 2054591, 2108417, 2163175,
+  2218873, 2275519, 2333121, 2391687, 2451225, 2511743, 2573249, 2635751,
+  2699257, 2763775, 2829313, 2895879, 2963481, 3032127, 3101825, 3172583,
+  3244409, 3317311, 3391297, 3466375, 3542553, 3619839, 3698241, 3777767,
+  3858425, 3940223, 4023169, 4107271, 4192537, 4278975, 4366593, 4455399,
+  4545401, 4636607, 4729025, 4822663, 4917529, 5013631, 5110977, 5209575,
+  5309433, 5410559, 5512961, 5616647, 5721625, 5827903, 5935489, 6044391,
+  6154617, 6266175, 6379073, 6493319, 6608921, 6725887, 6844225, 6963943,
+  7085049, 7207551,
+#if defined(CUSTOM_MODES)
+  /*...208:*/
+  7331457, 7456775, 7583513, 7711679, 7841281, 7972327, 8104825, 8238783,
+  8374209, 8511111, 8649497, 8789375, 8930753, 9073639, 9218041, 9363967,
+  9511425, 9660423, 9810969, 9963071, 10116737, 10271975, 10428793, 10587199,
+  10747201, 10908807, 11072025, 11236863, 11403329, 11571431, 11741177,
+  11912575,
+#endif
+  /*N=5, K=5...176:*/
+  321, 681, 1289, 2241, 3649, 5641, 8361, 11969, 16641, 22569, 29961, 39041,
+  50049, 63241, 78889, 97281, 118721, 143529, 172041, 204609, 241601, 283401,
+  330409, 383041, 441729, 506921, 579081, 658689, 746241, 842249, 947241,
+  1061761, 1186369, 1321641, 1468169, 1626561, 1797441, 1981449, 2179241,
+  2391489, 2618881, 2862121, 3121929, 3399041, 3694209, 4008201, 4341801,
+  4695809, 5071041, 5468329, 5888521, 6332481, 6801089, 7295241, 7815849,
+  8363841, 8940161, 9545769, 10181641, 10848769, 11548161, 12280841, 13047849,
+  13850241, 14689089, 15565481, 16480521, 17435329, 18431041, 19468809,
+  20549801, 21675201, 22846209, 24064041, 25329929, 26645121, 28010881,
+  29428489, 30899241, 32424449, 34005441, 35643561, 37340169, 39096641,
+  40914369, 42794761, 44739241, 46749249, 48826241, 50971689, 53187081,
+  55473921, 57833729, 60268041, 62778409, 65366401, 68033601, 70781609,
+  73612041, 76526529, 79526721, 82614281, 85790889, 89058241, 92418049,
+  95872041, 99421961, 103069569, 106816641, 110664969, 114616361, 118672641,
+  122835649, 127107241, 131489289, 135983681, 140592321, 145317129, 150160041,
+  155123009, 160208001, 165417001, 170752009, 176215041, 181808129, 187533321,
+  193392681, 199388289, 205522241, 211796649, 218213641, 224775361, 231483969,
+  238341641, 245350569, 252512961, 259831041, 267307049, 274943241, 282741889,
+  290705281, 298835721, 307135529, 315607041, 324252609, 333074601, 342075401,
+  351257409, 360623041, 370174729, 379914921, 389846081, 399970689, 410291241,
+  420810249, 431530241, 442453761, 453583369, 464921641, 476471169, 488234561,
+  500214441, 512413449, 524834241, 537479489, 550351881, 563454121, 576788929,
+  590359041, 604167209, 618216201, 632508801,
+#if defined(CUSTOM_MODES)
+  /*...208:*/
+  647047809, 661836041, 676876329, 692171521, 707724481, 723538089, 739615241,
+  755958849, 772571841, 789457161, 806617769, 824056641, 841776769, 859781161,
+  878072841, 896654849, 915530241, 934702089, 954173481, 973947521, 994027329,
+  1014416041, 1035116809, 1056132801, 1077467201, 1099123209, 1121104041,
+  1143412929, 1166053121, 1189027881, 1212340489, 1235994241,
+#endif
+  /*N=6, K=6...96:*/
+  1683, 3653, 7183, 13073, 22363, 36365, 56695, 85305, 124515, 177045, 246047,
+  335137, 448427, 590557, 766727, 982729, 1244979, 1560549, 1937199, 2383409,
+  2908411, 3522221, 4235671, 5060441, 6009091, 7095093, 8332863, 9737793,
+  11326283, 13115773, 15124775, 17372905, 19880915, 22670725, 25765455,
+  29189457, 32968347, 37129037, 41699767, 46710137, 52191139, 58175189,
+  64696159, 71789409, 79491819, 87841821, 96879431, 106646281, 117185651,
+  128542501, 140763503, 153897073, 167993403, 183104493, 199284183, 216588185,
+  235074115, 254801525, 275831935, 298228865, 322057867, 347386557, 374284647,
+  402823977, 433078547, 465124549, 499040399, 534906769, 572806619, 612825229,
+  655050231, 699571641, 746481891, 795875861, 847850911, 902506913, 959946283,
+  1020274013, 1083597703, 1150027593, 1219676595, 1292660325, 1369097135,
+  1449108145, 1532817275, 1620351277, 1711839767, 1807415257, 1907213187,
+  2011371957, 2120032959,
+#if defined(CUSTOM_MODES)
+  /*...109:*/
+  2233340609U, 2351442379U, 2474488829U, 2602633639U, 2736033641U, 2874848851U,
+  3019242501U, 3169381071U, 3325434321U, 3487575323U, 3655980493U, 3830829623U,
+  4012305913U,
+#endif
+  /*N=7, K=7...54*/
+  8989, 19825, 40081, 75517, 134245, 227305, 369305, 579125, 880685, 1303777,
+  1884961, 2668525, 3707509, 5064793, 6814249, 9041957, 11847485, 15345233,
+  19665841, 24957661, 31388293, 39146185, 48442297, 59511829, 72616013,
+  88043969, 106114625, 127178701, 151620757, 179861305, 212358985, 249612805,
+  292164445, 340600625, 395555537, 457713341, 527810725, 606639529, 695049433,
+  793950709, 904317037, 1027188385, 1163673953, 1314955181, 1482288821,
+  1667010073, 1870535785, 2094367717,
+#if defined(CUSTOM_MODES)
+  /*...60:*/
+  2340095869U, 2609401873U, 2904062449U, 3225952925U, 3577050821U, 3959439497U,
+#endif
+  /*N=8, K=8...37*/
+  48639, 108545, 224143, 433905, 795455, 1392065, 2340495, 3800305, 5984767,
+  9173505, 13726991, 20103025, 28875327, 40754369, 56610575, 77500017,
+  104692735, 139703809, 184327311, 240673265, 311207743, 398796225, 506750351,
+  638878193, 799538175, 993696769, 1226990095, 1505789553, 1837271615,
+  2229491905U,
+#if defined(CUSTOM_MODES)
+  /*...40:*/
+  2691463695U, 3233240945U, 3866006015U,
+#endif
+  /*N=9, K=9...28:*/
+  265729, 598417, 1256465, 2485825, 4673345, 8405905, 14546705, 24331777,
+  39490049, 62390545, 96220561, 145198913, 214828609, 312193553, 446304145,
+  628496897, 872893441, 1196924561, 1621925137, 2173806145U,
+#if defined(CUSTOM_MODES)
+  /*...29:*/
+  2883810113U,
+#endif
+  /*N=10, K=10...24:*/
+  1462563, 3317445, 7059735, 14218905, 27298155, 50250765, 89129247, 152951073,
+  254831667, 413442773, 654862247, 1014889769, 1541911931, 2300409629U,
+  3375210671U,
+  /*N=11, K=11...19:*/
+  8097453, 18474633, 39753273, 81270333, 158819253, 298199265, 540279585,
+  948062325, 1616336765,
+#if defined(CUSTOM_MODES)
+  /*...20:*/
+  2684641785U,
+#endif
+  /*N=12, K=12...18:*/
+  45046719, 103274625, 224298231, 464387817, 921406335, 1759885185,
+  3248227095U,
+  /*N=13, K=13...16:*/
+  251595969, 579168825, 1267854873, 2653649025U,
+  /*N=14, K=14:*/
+  1409933619
+};
 
-/*Compute V(2,_k).*/
-static inline opus_uint32 ncwrs2(int _k){
-  celt_assert(_k>0);
-  return 4*(opus_uint32)_k;
+#if defined(CUSTOM_MODES)
+const opus_uint32 *const CELT_PVQ_U_ROW[15]={
+  CELT_PVQ_U_DATA+   0,CELT_PVQ_U_DATA+ 208,CELT_PVQ_U_DATA+ 415,
+  CELT_PVQ_U_DATA+ 621,CELT_PVQ_U_DATA+ 826,CELT_PVQ_U_DATA+1030,
+  CELT_PVQ_U_DATA+1233,CELT_PVQ_U_DATA+1336,CELT_PVQ_U_DATA+1389,
+  CELT_PVQ_U_DATA+1421,CELT_PVQ_U_DATA+1441,CELT_PVQ_U_DATA+1455,
+  CELT_PVQ_U_DATA+1464,CELT_PVQ_U_DATA+1470,CELT_PVQ_U_DATA+1473
+};
+#else
+const opus_uint32 *const CELT_PVQ_U_ROW[15]={
+  CELT_PVQ_U_DATA+   0,CELT_PVQ_U_DATA+ 176,CELT_PVQ_U_DATA+ 351,
+  CELT_PVQ_U_DATA+ 525,CELT_PVQ_U_DATA+ 698,CELT_PVQ_U_DATA+ 870,
+  CELT_PVQ_U_DATA+1041,CELT_PVQ_U_DATA+1131,CELT_PVQ_U_DATA+1178,
+  CELT_PVQ_U_DATA+1207,CELT_PVQ_U_DATA+1226,CELT_PVQ_U_DATA+1240,
+  CELT_PVQ_U_DATA+1248,CELT_PVQ_U_DATA+1254,CELT_PVQ_U_DATA+1257
+};
+#endif
+
+#if defined(CUSTOM_MODES)
+void get_required_bits(opus_int16 *_bits,int _n,int _maxk,int _frac){
+  int k;
+  /*_maxk==0 => there's nothing to do.*/
+  celt_assert(_maxk>0);
+  _bits[0]=0;
+  for(k=1;k<=_maxk;k++)_bits[k]=log2_frac(CELT_PVQ_V(_n,k),_frac);
 }
+#endif
 
-/*Compute U(3,_k).
-  Note that this may be called with _k=32768 (maxK[3]+1).*/
-static inline opus_uint32 ucwrs3(unsigned _k){
-  celt_assert(_k>0);
-  return (2*(opus_uint32)_k-2)*_k+1;
+static opus_uint32 icwrs(int _n,const int *_y){
+  opus_uint32 i;
+  int         j;
+  int         k;
+  celt_assert(_n>=2);
+  j=_n-1;
+  i=_y[j]<0;
+  k=abs(_y[j]);
+  do{
+    j--;
+    i+=CELT_PVQ_U(_n-j,k);
+    k+=abs(_y[j]);
+    if(_y[j]<0)i+=CELT_PVQ_U(_n-j,k+1);
+  }
+  while(j>0);
+  return i;
 }
 
-/*Compute V(3,_k).*/
-static inline opus_uint32 ncwrs3(int _k){
+void encode_pulses(const int *_y,int _n,int _k,ec_enc *_enc){
   celt_assert(_k>0);
-  return 2*(2*(unsigned)_k*(opus_uint32)_k+1);
+  ec_enc_uint(_enc,icwrs(_n,_y),CELT_PVQ_V(_n,_k));
 }
 
-/*Compute U(4,_k).*/
-static inline opus_uint32 ucwrs4(int _k){
+static void cwrsi(int _n,int _k,opus_uint32 _i,int *_y){
   celt_assert(_k>0);
-  return imusdiv32odd(2*_k,(2*_k-3)*(opus_uint32)_k+4,3,1);
+  celt_assert(_n>0);
+  do{
+    opus_uint32 p;
+    int         s;
+    int         k0;
+    /*Are the pulses in this dimension negative?*/
+    p=CELT_PVQ_U(_n,_k+1);
+    s=-(_i>=p);
+    _i-=p&s;
+    /*Count how many pulses were placed in this dimension.*/
+    k0=_k;
+    for(p=CELT_PVQ_U(_n,_k);p>_i;p=CELT_PVQ_U(_n,_k))_k--;
+    _i-=p;
+    *_y++=(k0-_k+s)^s;
+  }
+  while(--_n>0);
 }
 
-/*Compute V(4,_k).*/
-static inline opus_uint32 ncwrs4(int _k){
-  celt_assert(_k>0);
-  return ((_k*(opus_uint32)_k+2)*_k)/3<<3;
+void decode_pulses(int *_y,int _n,int _k,ec_dec *_dec){
+  cwrsi(_n,_k,ec_dec_uint(_dec,CELT_PVQ_V(_n,_k)),_y);
 }
 
-#endif /* SMALL_FOOTPRINT */
+#else /* SMALL_FOOTPRINT */
 
 /*Computes the next row/column of any recurrence that obeys the relation
    u[i][j]=u[i-1][j]+u[i][j-1]+u[i-1][j-1].
@@ -332,125 +529,18 @@ static opus_uint32 ncwrs_urow(unsigned _n,unsigned _k,opus_uint32 *_u){
   celt_assert(len>=3);
   _u[0]=0;
   _u[1]=um2=1;
-#ifndef SMALL_FOOTPRINT
-  /*_k>52 doesn't work in the false branch due to the limits of INV_TABLE,
-    but _k isn't tested here because k<=52 for n=7*/
-  if(_n<=6)
-#endif
-  {
-    /*If _n==0, _u[0] should be 1 and the rest should be 0.*/
-    /*If _n==1, _u[i] should be 1 for i>1.*/
-    celt_assert(_n>=2);
-    /*If _k==0, the following do-while loop will overflow the buffer.*/
-    celt_assert(_k>0);
-    k=2;
-    do _u[k]=(k<<1)-1;
-    while(++k<len);
-    for(k=2;k<_n;k++)unext(_u+1,_k+1,1);
-  }
-#ifndef SMALL_FOOTPRINT
-  else{
-    opus_uint32 um1;
-    opus_uint32 n2m1;
-    _u[2]=n2m1=um1=(_n<<1)-1;
-    for(k=3;k<len;k++){
-      /*U(N,K) = ((2*N-1)*U(N,K-1)-U(N,K-2))/(K-1) + U(N,K-2)*/
-      _u[k]=um2=imusdiv32even(n2m1,um1,um2,k-1)+um2;
-      if(++k>=len)break;
-      _u[k]=um1=imusdiv32odd(n2m1,um2,um1,(k-1)>>1)+um1;
-    }
-  }
-#endif /* SMALL_FOOTPRINT */
+  /*If _n==0, _u[0] should be 1 and the rest should be 0.*/
+  /*If _n==1, _u[i] should be 1 for i>1.*/
+  celt_assert(_n>=2);
+  /*If _k==0, the following do-while loop will overflow the buffer.*/
+  celt_assert(_k>0);
+  k=2;
+  do _u[k]=(k<<1)-1;
+  while(++k<len);
+  for(k=2;k<_n;k++)unext(_u+1,_k+1,1);
   return _u[_k]+_u[_k+1];
 }
 
-#ifndef SMALL_FOOTPRINT
-
-/*Returns the _i'th combination of _k elements (at most 32767) chosen from a
-   set of size 1 with associated sign bits.
-  _y: Returns the vector of pulses.*/
-static inline void cwrsi1(int _k,opus_uint32 _i,int *_y){
-  int s;
-  s=-(int)_i;
-  _y[0]=(_k+s)^s;
-}
-
-/*Returns the _i'th combination of _k elements (at most 32767) chosen from a
-   set of size 2 with associated sign bits.
-  _y: Returns the vector of pulses.*/
-static inline void cwrsi2(int _k,opus_uint32 _i,int *_y){
-  opus_uint32 p;
-  int           s;
-  int           yj;
-  p=ucwrs2(_k+1U);
-  s=-(_i>=p);
-  _i-=p&s;
-  yj=_k;
-  _k=(_i+1)>>1;
-  p=_k?ucwrs2(_k):0;
-  _i-=p;
-  yj-=_k;
-  _y[0]=(yj+s)^s;
-  cwrsi1(_k,_i,_y+1);
-}
-
-/*Returns the _i'th combination of _k elements (at most 32767) chosen from a
-   set of size 3 with associated sign bits.
-  _y: Returns the vector of pulses.*/
-static void cwrsi3(int _k,opus_uint32 _i,int *_y){
-  opus_uint32 p;
-  int           s;
-  int           yj;
-  p=ucwrs3(_k+1U);
-  s=-(_i>=p);
-  _i-=p&s;
-  yj=_k;
-  /*Finds the maximum _k such that ucwrs3(_k)<=_i (tested for all
-     _i<2147418113=U(3,32768)).*/
-  _k=_i>0?(isqrt32(2*_i-1)+1)>>1:0;
-  p=_k?ucwrs3(_k):0;
-  _i-=p;
-  yj-=_k;
-  _y[0]=(yj+s)^s;
-  cwrsi2(_k,_i,_y+1);
-}
-
-/*Returns the _i'th combination of _k elements (at most 1172) chosen from a set
-   of size 4 with associated sign bits.
-  _y: Returns the vector of pulses.*/
-static void cwrsi4(int _k,opus_uint32 _i,int *_y){
-  opus_uint32 p;
-  int           s;
-  int           yj;
-  int           kl;
-  int           kr;
-  p=ucwrs4(_k+1);
-  s=-(_i>=p);
-  _i-=p&s;
-  yj=_k;
-  /*We could solve a cubic for k here, but the form of the direct solution does
-     not lend itself well to exact integer arithmetic.
-    Instead we do a binary search on U(4,K).*/
-  kl=0;
-  kr=_k;
-  for(;;){
-    _k=(kl+kr)>>1;
-    p=_k?ucwrs4(_k):0;
-    if(p<_i){
-      if(_k>=kr)break;
-      kl=_k+1;
-    }
-    else if(p>_i)kr=_k-1;
-    else break;
-  }
-  _i-=p;
-  yj-=_k;
-  _y[0]=(yj+s)^s;
-  cwrsi3(_k,_i,_y+1);
-}
-
-#endif /* SMALL_FOOTPRINT */
-
 /*Returns the _i'th combination of _k elements chosen from a set of size _n
    with associated sign bits.
   _y: Returns the vector of pulses.
@@ -487,55 +577,6 @@ static inline opus_uint32 icwrs1(const int *_y,int *_k){
   return _y[0]<0;
 }
 
-#ifndef SMALL_FOOTPRINT
-
-/*Returns the index of the given combination of K elements chosen from a set
-   of size 2 with associated sign bits.
-  _y: The vector of pulses, whose sum of absolute values is K.
-  _k: Returns K.*/
-static inline opus_uint32 icwrs2(const int *_y,int *_k){
-  opus_uint32 i;
-  int           k;
-  i=icwrs1(_y+1,&k);
-  i+=k?ucwrs2(k):0;
-  k+=abs(_y[0]);
-  if(_y[0]<0)i+=ucwrs2(k+1U);
-  *_k=k;
-  return i;
-}
-
-/*Returns the index of the given combination of K elements chosen from a set
-   of size 3 with associated sign bits.
-  _y: The vector of pulses, whose sum of absolute values is K.
-  _k: Returns K.*/
-static inline opus_uint32 icwrs3(const int *_y,int *_k){
-  opus_uint32 i;
-  int           k;
-  i=icwrs2(_y+1,&k);
-  i+=k?ucwrs3(k):0;
-  k+=abs(_y[0]);
-  if(_y[0]<0)i+=ucwrs3(k+1U);
-  *_k=k;
-  return i;
-}
-
-/*Returns the index of the given combination of K elements chosen from a set
-   of size 4 with associated sign bits.
-  _y: The vector of pulses, whose sum of absolute values is K.
-  _k: Returns K.*/
-static inline opus_uint32 icwrs4(const int *_y,int *_k){
-  opus_uint32 i;
-  int           k;
-  i=icwrs3(_y+1,&k);
-  i+=k?ucwrs4(k):0;
-  k+=abs(_y[0]);
-  if(_y[0]<0)i+=ucwrs4(k+1);
-  *_k=k;
-  return i;
-}
-
-#endif /* SMALL_FOOTPRINT */
-
 /*Returns the index of the given combination of K elements chosen from a set
    of size _n with associated sign bits.
   _y:  The vector of pulses, whose sum of absolute values must be _k.
@@ -543,8 +584,8 @@ static inline opus_uint32 icwrs4(const int *_y,int *_k){
 static inline opus_uint32 icwrs(int _n,int _k,opus_uint32 *_nc,const int *_y,
  opus_uint32 *_u){
   opus_uint32 i;
-  int           j;
-  int           k;
+  int         j;
+  int         k;
   /*We can't unroll the first two iterations of the loop unless _n>=2.*/
   celt_assert(_n>=2);
   _u[0]=0;
@@ -589,57 +630,23 @@ void get_required_bits(opus_int16 *_bits,int _n,int _maxk,int _frac){
 
 void encode_pulses(const int *_y,int _n,int _k,ec_enc *_enc){
   opus_uint32 i;
+  VARDECL(opus_uint32,u);
+  opus_uint32 nc;
+  SAVE_STACK;
   celt_assert(_k>0);
-#ifndef SMALL_FOOTPRINT
-  switch(_n){
-    case 2:{
-      i=icwrs2(_y,&_k);
-      ec_enc_uint(_enc,i,ncwrs2(_k));
-    }break;
-    case 3:{
-      i=icwrs3(_y,&_k);
-      ec_enc_uint(_enc,i,ncwrs3(_k));
-    }break;
-    case 4:{
-      i=icwrs4(_y,&_k);
-      ec_enc_uint(_enc,i,ncwrs4(_k));
-    }break;
-     default:
-    {
-#endif
-      VARDECL(opus_uint32,u);
-      opus_uint32 nc;
-      SAVE_STACK;
-      ALLOC(u,_k+2U,opus_uint32);
-      i=icwrs(_n,_k,&nc,_y,u);
-      ec_enc_uint(_enc,i,nc);
-      RESTORE_STACK;
-#ifndef SMALL_FOOTPRINT
-    }
-    break;
-  }
-#endif
+  ALLOC(u,_k+2U,opus_uint32);
+  i=icwrs(_n,_k,&nc,_y,u);
+  ec_enc_uint(_enc,i,nc);
+  RESTORE_STACK;
 }
 
-void decode_pulses(int *_y,int _n,int _k,ec_dec *_dec)
-{
+void decode_pulses(int *_y,int _n,int _k,ec_dec *_dec){
+  VARDECL(opus_uint32,u);
+  SAVE_STACK;
   celt_assert(_k>0);
-#ifndef SMALL_FOOTPRINT
-   switch(_n){
-    case 2:cwrsi2(_k,ec_dec_uint(_dec,ncwrs2(_k)),_y);break;
-    case 3:cwrsi3(_k,ec_dec_uint(_dec,ncwrs3(_k)),_y);break;
-    case 4:cwrsi4(_k,ec_dec_uint(_dec,ncwrs4(_k)),_y);break;
-    default:
-    {
-#endif
-      VARDECL(opus_uint32,u);
-      SAVE_STACK;
-      ALLOC(u,_k+2U,opus_uint32);
-      cwrsi(_n,_k,ec_dec_uint(_dec,ncwrs_urow(_n,_k,u)),_y,u);
-      RESTORE_STACK;
-#ifndef SMALL_FOOTPRINT
-    }
-    break;
-  }
-#endif
+  ALLOC(u,_k+2U,opus_uint32);
+  cwrsi(_n,_k,ec_dec_uint(_dec,ncwrs_urow(_n,_k,u)),_y,u);
+  RESTORE_STACK;
 }
+
+#endif /* SMALL_FOOTPRINT */