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C/C++ Source or Header  |  1999-12-03  |  16.0 KB  |  492 lines
  1. /* Public domain .ra/28_8 file decoder v2.0 */
  2.  
  3. /* Usage: radecode2 <file.ra >output.dat */
  4. /* Output is signed 16-bit audio data, 8khz */
  5.  
  6. #include <stdio.h>
  7. #include <unistd.h>
  8. #include <math.h>
  9.  
  10. /* globals */
  11. static float history[8];
  12. static float output[40];
  13. static float pr1[36];
  14. static float pr2[10];
  15. static int phase,phasep;
  16.  
  17. char version[]="$VER: RAdecode 2.0 (22.10.98) The Amiga RealAudio decoder, thanks to all!";
  18.  
  19. int main()
  20. {
  21.   unsigned int x;
  22.   unsigned char in[2736];
  23.   unsigned char deint[2736];
  24.   signed short out[160];
  25.  
  26.   read(0,in,12);
  27.   if(in[0]!='.'||in[1]!='r'||in[2]!='a'||in[3]!=0xfd||
  28.      in[4]!=0||in[5]!=4||in[6]!=0||in[7]!=0||
  29.      in[8]!='.'||in[9]!='r'||in[10]!='a'||in[11]!='4')
  30.   {
  31.     fprintf(stderr,"Unrecognized format\n");fflush(stderr);exit(1);
  32.   }
  33.   read(0,in,6);
  34.   read(0,in,4);
  35.   x=(in[0]<<24|in[1]<<16|in[2]<<8|in[3])-6;
  36.   lseek(0,x,SEEK_CUR);
  37.   
  38.   while(read(0,in,2736)>0){
  39.     deinterleave(in,deint);
  40.     for(x=0;x<72;x++){
  41.       decodeblock(deint+38*x,out);
  42.       write(1,out,160*2);
  43.     }
  44.   }
  45.   return 0;
  46. }
  47.  
  48. /* Unlike the 14.4 format, 28.8 blocks are interleaved */
  49. /* to dilute the effects of transmission errors */
  50. deinterleave(unsigned char *in,unsigned char *out)
  51. {
  52.   unsigned int x=0,y=0;
  53.   while(x<2736)
  54.   {
  55.     memcpy(out+y,in+x,38);
  56.     x+=38;y+=456;
  57.     if(y>=2736) y-=2698;
  58.   }
  59. }
  60.  
  61. /* Decode a block (celp) */
  62. decodeblock(char *in,short int *out)
  63. {
  64.   int x,y;
  65.   unsigned short int buffer[32];
  66.  
  67.   unpack(buffer,in,32);
  68.   for(x=0;x<32;x++)
  69.   {
  70.     phasep=(phase=x&7)*5;
  71.     decode(buffer[x]);
  72.     for(y=0;y<5;y++) *(out++)=8*output[phasep+y];
  73.     if(phase==3) update();
  74.   }
  75. }
  76.  
  77. /* initial decode */
  78. unpack(unsigned short *tgt,unsigned char *src,int len)
  79. {
  80.   int x,y,z;
  81.   int n,temp;
  82.   int buffer[38];
  83.  
  84.   for(x=0;x<len;x++) {
  85.     tgt[x]=0;
  86.     buffer[x]=9+(x&1);
  87.   }
  88.  
  89.   for(x=y=z=0;x<38;x++) {
  90.     n=buffer[y]-z;
  91.     temp=src[x];
  92.     if(n<8) temp&=255>>(8-n);
  93.     tgt[y]+=temp<<z;
  94.     if(n<=8) {
  95.       tgt[++y]+=src[x]>>n;
  96.       z=8-n;
  97.     } else z+=8;
  98.   }
  99. }
  100.  
  101. float amptable[8]={0.515625,0.90234375,1.57910156,2.76342773,
  102.                -0.515625,-0.90234375,-1.57910156,-2.76342773};
  103.  
  104. float codetable[640]={
  105.  
  106. 0.326171875,-1.4404296875,-0.6123046875,-0.8740234375,-1.24658203125,
  107.   -2.45703125,-2.23486328125,-0.51025390625,1.419921875,1.6201171875,
  108.  
  109. -1.37646484375,-1.30712890625,-0.462890625,-1.37939453125,-2.1728515625,
  110.   -3.26123046875,-0.166015625,0.7236328125,-0.623046875,0.6162109375,
  111.  
  112. -0.2744140625,-3.29931640625,0.62548828125,0.08740234375,-0.6220703125,
  113.   -1.2265625,-3.4814453125,-2.40478515625,3.37548828125,1.17724609375,
  114.   -1.2099609375,-0.076171875,2.28662109375,-1.89111328125,0,
  115.   -4.0078125,1.044921875,-0.2333984375,-1.35986328125,0.26025390625,
  116.  
  117. 0.92236328125,1.34716796875,0.67431640625,-3.39599609375,-2.88720703125,
  118.   2.4814453125,-1.201171875,-2.8212890625,0.87744140625,0.27734375,
  119.   -1.078125,-1.61572265625,-2.20849609375,-3.044921875,-3.66455078125,
  120.   -1.32763671875,2.1279296875,-1.458984375,-0.56103515625,1.30078125,
  121.   0.61474609375,0.48583984375,1.32373046875,-1.203125,-5.0732421875,
  122.  
  123. 0.8408203125,-3.69580078125,-1.3388671875,1.06005859375,-1.13720703125,
  124.   0.50390625,0.36474609375,-0.4189453125,-3.8798828125,-6.27099609375,
  125.   1.5166015625,2.37109375,-2.04736328125,-1.24072265625,0.50537109375,
  126.   0.9091796875,-0.46875,-3.236328125,0.2001953125,2.8720703125,
  127.   -1.21728515625,-1.283203125,-1.953125,-0.029296875,3.5166015625,
  128.   -1.3046875,0.7060546875,0.75,-1.87060546875,0.60205078125,
  129.   -2.5888671875,3.375,0.77587890625,-2.04443359375,1.78955078125,
  130.   -1.6875,-3.9892578125,-3.76416015625,0.67578125,2.2939453125,
  131.   -2.29443359375,-3.03173828125,-5.45703125,3.95703125,8.2177734375,
  132.   0.4541015625,3.419921875,0.61962890625,-4.38330078125,1.25341796875,
  133.  
  134. 2.27001953125,5.763671875,1.68017578125,-2.76220703125,0.58544921875,
  135.   1.2412109375,-0.08935546875,-4.32568359375,-3.89453125,1.5771484375,
  136.  
  137. -1.40234375,-0.98193359375,-4.74267578125,-4.09423828125,6.33935546875,
  138.   1.5068359375,1.044921875,-1.796875,-4.70849609375,-1.4140625,
  139.  
  140. -3.71533203125,3.18115234375,-1.11474609375,-1.2314453125,3.091796875,
  141.  
  142. -1.62744140625,-2.744140625,-4.4580078125,-5.43505859375,2.70654296875,
  143.  
  144. -0.19873046875,-3.28173828125,-8.5283203125,-1.41064453125,5.6484375,
  145.   1.802734375,3.318359375,-0.1279296875,-5.2958984375,-0.90625,
  146.   3.55224609375,6.544921875,-1.45947265625,-5.17333984375,2.41015625,
  147.   0.119140625,-1.08349609375,1.296875,1.84375,-2.642578125,
  148.  
  149. -1.97412109375,-2.8974609375,1.04052734375,0.42138671875,-1.3994140625,
  150.   -1.6123046875,0.85107421875,-0.9794921875,-0.0625,-1.001953125,
  151.  
  152. -3.10595703125,1.6318359375,-0.77294921875,-0.01025390625,0.5576171875,
  153.   -1.87353515625,-0.89404296875,3.12353515625,1.24267578125,-1.390625,
  154.   -4.556640625,-3.1875,2.59228515625,0.9697265625,-1.09619140625,
  155.  
  156. -2.1923828125,0.365234375,0.94482421875,-1.47802734375,-0.24072265625,
  157.   -4.51904296875,2.6201171875,1.55908203125,-2.19384765625,0.87109375,
  158.   2.3359375,-0.1806640625,0.9111328125,0.51611328125,-0.92236328125,
  159.  
  160. 3.5849609375,-1.3134765625,-1.25830078125,0.330078125,-0.29833984375,
  161.  
  162. -0.2451171875,1.09130859375,-0.9033203125,-0.86767578125,-1.00048828125,
  163.   0.49365234375,1.89453125,-1.20361328125,1.07861328125,-0.07421875,
  164.   1.265625,1.38134765625,2.728515625,1.38623046875,-3.5673828125,
  165.  
  166. -1.48876953125,-2.4013671875,2.90771484375,4.49267578125,-2.17138671875,
  167.   0.34033203125,1.908203125,2.8310546875,-2.17333984375,-2.267578125,
  168.  
  169. -1.03564453125,2.658203125,-1.2548828125,0.15673828125,-0.5869140625,
  170.   1.3896484375,-1.0185546875,1.724609375,0.2763671875,-0.345703125,
  171.   -2.08935546875,0.4638671875,2.431640625,1.83056640625,0.220703125,
  172.   -1.212890625,1.7099609375,0.83935546875,-0.0830078125,0.1162109375,
  173.  
  174. -1.67724609375,0.12841796875,1.0322265625,-0.97900390625,1.15283203125,
  175.   -3.5830078125,-0.58984375,4.56396484375,-0.59375,-1.95947265625,
  176.   -6.5908203125,-0.21435546875,3.919921875,-2.06640625,0.17626953125,
  177.  
  178. -1.82080078125,2.65283203125,0.978515625,-2.30810546875,-0.61474609375,
  179.  
  180. -1.9462890625,3.78076171875,4.11572265625,-1.80224609375,-0.48193359375,
  181.   2.5380859375,-0.20654296875,0.5615234375,-0.62548828125,0.3984375,
  182.  
  183. 3.61767578125,2.00634765625,-1.92822265625,1.3134765625,0.0146484384313,
  184.  
  185. 0.6083984375,1.49169921875,-0.01708984375,-0.6689453125,-0.1201171875,
  186.  
  187. -0.72705078125,2.75146484375,-0.3310546875,-1.28271484375,1.5478515625,
  188.   2.3583984375,-2.23876953125,0.98046875,-0.5185546875,0.39013671875,
  189.  
  190. -0.06298828125,0.35009765625,2.2431640625,7.29345703125,5.2275390625,
  191.  
  192. 0.20361328125,1.34716796875,0.9033203125,-2.46923828125,-0.56298828125,
  193.   -1.89794921875,3.59423828125,-2.81640625,2.09228515625,0.3251953125,
  194.  
  195. 0.70458984375,-0.4580078125,0.009765625,-1.03466796875,-0.82861328125,
  196.   -1.8125,-1.6611328125,-1.080078125,0.0537109375,1.04296875,
  197.   -1.44140625,0.005859375,-0.765625,-1.708984375,-0.90576171875,
  198.  
  199. -0.64208984375,-0.84521484375,0.56640625,-0.2724609375,0.83447265625,
  200.   0.04296875,-2.23095703125,0.0947265625,-0.2216796875,-1.44384765625,
  201.  
  202. -1.38623046875,-0.8134765625,-0.13330078125,1.017578125,-0.07568359375,
  203.   -0.09228515625,-1.16015625,0.81201171875,-0.5078125,-1.19580078125,
  204.   -1.3876953125,-0.66845703125,0.310546875,-0.12109375,-1.30712890625,
  205.  
  206. 0.74072265625,0.03857421875,-1.47119140625,-1.79150390625,-0.47509765625,
  207.   0.93408203125,-1.21728515625,-2.59375,-0.36572265625,0.62060546875,
  208.  
  209. -1.41748046875,-1.623046875,-1.833984375,-1.8017578125,-0.89306640625,
  210.   -1.42236328125,-0.75537109375,-1.34765625,-0.6865234375,0.548828125,
  211.   0.900390625,-0.8955078125,0.22265625,0.3447265625,-2.0859375,
  212.   0.22802734375,-2.078125,-0.93212890625,0.74267578125,0.5537109375,
  213.  
  214. -0.06201171875,-0.4853515625,-0.31103515625,-0.72802734375,-3.1708984375,
  215.   0.42626953125,-0.99853515625,-1.869140625,-1.36328125,-0.2822265625,
  216.   1.12841796875,-0.88720703125,1.28515625,-1.490234375,0.9609375,
  217.   0.31298828125,0.5830078125,0.92431640625,2.00537109375,3.0966796875,
  218.   -0.02197265625,0.5849609375,1.0546875,-0.70751953125,1.07568359375,
  219.   -0.978515625,0.83642578125,1.7177734375,1.294921875,2.07568359375,
  220.   1.43359375,-1.9375,0.625,0.06396484375,-0.720703125,
  221.   1.38037109375,0.00390625,-0.94140625,1.2978515625,1.71533203125,
  222.  
  223. 1.56201171875,-0.3984375,1.31201171875,-0.85009765625,-0.68701171875,
  224.   1.439453125,1.96728515625,0.1923828125,-0.12353515625,0.6337890625,
  225.   2.0927734375,0.02490234375,-2.20068359375,-0.015625,-0.32177734375,
  226.   1.90576171875,2.7568359375,-2.728515625,-1.265625,2.78662109375,
  227.   -0.2958984375,0.6025390625,-0.78466796875,-2.53271484375,0.32421875,
  228.   -0.25634765625,1.767578125,-1.0703125,-1.23388671875,0.83349609375,
  229.   2.09814453125,-1.58740234375,-1.11474609375,0.396484375,-1.10546875,
  230.   2.81494140625,0.2578125,-1.60498046875,0.66015625,0.81640625,
  231.  
  232. 1.33544921875,0.60595703125,-0.53857421875,-1.59814453125,-1.66357421875,
  233.   1.96923828125,0.8046875,-1.44775390625,-0.5732421875,0.705078125,
  234.   0.0361328125,0.4482421875,0.97607421875,0.44677734375,-0.5009765625,
  235.   -1.21875,-0.78369140625,0.9931640625,1.4404296875,0.11181640625,
  236.   -1.05859375,0.99462890625,0.00732421921566,-0.6171875,-0.1015625,
  237.   -1.734375,0.7470703125,0.28369140625,0.72802734375,0.4697265625,
  238.  
  239. -1.27587890625,-1.1416015625,1.76806640625,-0.7265625,-1.06689453125,
  240.   -0.85302734375,0.03955078125,2.7041015625,0.69921875,-1.10205078125,
  241.  
  242. -0.49755859375,0.42333984375,0.1044921875,-1.115234375,-0.7373046875,
  243.   -0.822265625,1.375,-0.11181640625,1.24560546875,-0.67822265625,
  244.   1.32177734375,0.24609375,0.23388671875,1.35888671875,-0.49267578125,
  245.  
  246. 1.22900390625,-0.72607421875,-0.779296875,0.30322265625,0.94189453125,
  247.   -0.072265625,1.0771484375,-2.09375,0.630859375,-0.68408203125,
  248.   -0.25732421875,0.60693359375,-1.33349609375,0.93212890625,0.625,
  249.   1.04931640625,-0.73291015625,1.80078125,0.2978515625,-2.24169921875,
  250.  
  251. 1.6142578125,-1.64501953125,0.91552734375,1.775390625,-0.59423828125,
  252.  
  253. 1.2568359375,1.22705078125,0.70751953125,-1.5009765625,-2.43115234375,
  254.  
  255. 0.3974609375,0.8916015625,-1.21923828125,2.0673828125,-1.99072265625,
  256.   0.8125,-0.107421875,1.6689453125,0.4892578125,0.54443359375,
  257.   0.38134765625,0.8095703125,1.91357421875,2.9931640625,1.533203125,
  258.   0.560546875,1.98486328125,0.740234375,0.39794921875,0.09716796875,
  259.  
  260. 0.58154296875,1.21533203125,1.25048828125,1.18212890625,1.19287109375,
  261.   0.3759765625,-2.88818359375,2.69287109375,-0.1796875,-1.56201171875,
  262.  
  263. 0.5810546875,0.51123046875,1.8271484375,3.38232421875,-1.02001953125,
  264.   0.142578125,1.51318359375,2.103515625,-0.3701171875,-1.19873046875,
  265.   0.25537109375,1.91455078125,1.974609375,0.6767578125,0.04150390625,
  266.  
  267. 2.13232421875,0.4912109375,-0.611328125,-0.7158203125,-0.67529296875,
  268.   1.880859375,0.77099609375,-0.03759765625,1.0078125,0.423828125,
  269.  
  270. 2.49462890625,1.42529296875,-0.0986328125,0.17529296875,-0.24853515625,
  271.   1.7822265625,1.5654296875,1.12451171875,0.82666015625,0.6328125,
  272.  
  273. 1.41845703125,-1.90771484375,0.11181640625,-0.583984375,-1.138671875,
  274.  
  275. 2.91845703125,-1.75048828125,0.39306640625,1.86767578125,-1.5322265625,
  276.  
  277. 1.8291015625,-0.2958984375,0.02587890625,-0.13134765625,-1.61181640625,
  278.   0.2958984375,0.9853515625,-0.642578125,1.984375,0.1943359375};
  279.  
  280. /* Decode and produce output */
  281. decode(unsigned int input)
  282. {
  283.   unsigned int x,y;
  284.   float f;
  285.   double sum;
  286.   float *p1,*p2;
  287.   float buffer[5];
  288.   static float sb[41];
  289.   static float lhist[10];
  290.  
  291.   for(x=36;x--;) sb[x+5]=sb[x];
  292.   for(x=5;x--;) {
  293.     p1=sb+x;p2=pr1;
  294.     sum=0;for(y=36;y--;) sum-=(*(++p1))*(*(p2++));
  295.     sb[x]=sum;
  296.   }
  297.  
  298.   f=amptable[input&7];
  299.   p1=codetable+(input>>3)*5;
  300.  
  301.   /* convert log and do rms */
  302.   sum=32;for(x=10;x--;) sum-=pr2[x]*lhist[x];
  303.   if(sum<0) sum=0; else if(sum>60) sum=60;
  304.   for(x=5;x--;) buffer[x]=f*p1[x]*pow(10,sum/20);
  305.   sum=0;for(x=5;x--;) sum+=buffer[x]*buffer[x];
  306.   if((sum/=5)<1) sum=1;
  307.   /* shift and store */
  308.   for(x=10;--x;) lhist[x]=lhist[x-1];
  309.   *lhist=history[phase]=10*log10(sum)-32;
  310.   
  311.   for(x=1;x<5;x++) for(y=x;y--;) buffer[x]-=pr1[x-y-1]*buffer[y];
  312.  
  313.   /* output */
  314.   for (x=0;x<5;x++) {
  315.     f=sb[4-x]+buffer[x];
  316.     if(f>4095) f=4095; else if(f<-4095) f=-4095;
  317.     output[phasep+x]=sb[4-x]=f;
  318.   }
  319. }
  320.  
  321. float table1[111]={
  322.  
  323. 0.576690972,0.580838025,0.585013986,0.589219987,0.59345597,0.597723007,
  324.  
  325. 0.602020264,0.606384277,0.610748291,0.615142822,0.619598389,0.624084473,
  326.  
  327. 0.628570557,0.633117676,0.637695313,0.642272949,0.646911621,0.651580811,
  328.  
  329. 0.656280518,0.66104126,0.665802002,0.670593262,0.675445557,0.680328369,
  330.  
  331. 0.685241699,0.690185547,0.695159912,0.700164795,0.705230713,0.710327148,
  332.  
  333. 0.715454102,0.720611572,0.725830078,0.731048584,0.736328125,0.741638184,
  334.  
  335. 0.747009277,0.752380371,0.7578125,0.763305664,0.768798828,0.774353027,
  336.  
  337. 0.779937744,0.785583496,0.791229248,0.796936035,0.802703857,0.808502197,
  338.  
  339. 0.814331055,0.820220947,0.826141357,0.832092285,0.838104248,0.844146729,
  340.  
  341. 0.850250244,0.856384277,0.862548828,0.868774414,0.875061035,0.881378174,
  342.  
  343. 0.88772583,0.894134521,0.900604248,0.907104492,0.913635254,0.920227051,
  344.  
  345. 0.926879883,0.933563232,0.940307617,0.94708252,0.953918457,0.96081543,
  346.  
  347. 0.96774292,0.974731445,0.981781006,0.988861084,0.994842529,0.998565674,
  348.  
  349. 0.999969482,0.99911499,0.996002197,0.990600586,0.982910156,0.973022461,
  350.  
  351. 0.960876465,0.946533203,0.930053711,0.911437988,0.89074707,0.868041992,
  352.  
  353. 0.843322754,0.816680908,0.788208008,0.757904053,0.725891113,0.692199707,
  354.  
  355. 0.656921387,0.620178223,0.582000732,0.542480469,0.501739502,0.459838867,
  356.  
  357. 0.416900635,0.373016357,0.328277588,0.282775879,0.236663818,0.189971924,
  358.   0.142852783,0.0954284668,0.0477600098};
  359.  
  360. float table2[38]={
  361.  
  362. 0.505699992,0.524200022,0.54339999,0.563300014,0.583953857,0.60534668,
  363.  
  364. 0.627502441,0.650482178,0.674316406,0.699005127,0.724578857,0.75112915,
  365.  
  366. 0.778625488,0.807128906,0.836669922,0.86730957,0.899078369,0.932006836,
  367.   0.961486816,0.982757568,0.995635986,1,0.995819092,0.983154297,
  368.  
  369. 0.96206665,0.932769775,0.895507813,0.850585938,0.798400879,0.739379883,
  370.  
  371. 0.674072266,0.602996826,0.526763916,0.446014404,0.361480713,0.273834229,
  372.   0.183868408,0.0923461914};
  373.  
  374. float table1a[36]={
  375.  
  376. 0.98828125,0.976699829,0.965254128,0.953942537,0.942763507,0.931715488,
  377.  
  378. 0.920796931,0.910006344,0.899342179,0.888803005,0.878387332,0.868093729,
  379.  
  380. 0.857920766,0.847867012,0.837931097,0.828111589,0.818407178,0.808816493,
  381.  
  382. 0.799338162,0.789970934,0.780713439,0.771564424,0.762522638,0.753586829,
  383.  
  384. 0.744755745,0.736028135,0.727402806,0.718878567,0.710454226,0.702128589,
  385.  
  386. 0.693900526,0.685768902,0.677732527,0.669790328,0.66194123,0.654184103};
  387.  
  388. float table2a[10]={
  389.   0.90625,0.821289063,0.74432373,0.674499512,0.61126709,
  390.   0.553955078,0.50201416,0.454956055,0.41229248,0.373657227};
  391.  
  392. update()
  393. {
  394.   int x,y;
  395.   float buffer1[40],temp1[37];
  396.   float buffer2[8],temp2[11];
  397.   static float st1a[111],st1b[37],st1[37];
  398.   static float st2a[38],st2b[11],st2[11];
  399.  
  400.   for(x=0,y=phasep+5;x<40;) buffer1[x++]=output[(y++)%40];
  401.   co(36,40,35,buffer1,temp1,st1a,st1b,table1);
  402.   if(pred(temp1,st1,36))
  403.     colmult(pr1,st1,table1a,36);
  404.  
  405.   for(x=0,y=phase+1;x<8;) buffer2[x++]=history[(y++)%8];
  406.   co(10,8,20,buffer2,temp2,st2a,st2b,table2);
  407.   if(pred(temp2,st2,10))
  408.     colmult(pr2,st2,table2a,10);
  409. }
  410.  
  411. /* column multiply */
  412. colmult(float *tgt,float *m1,float *m2,int n)
  413. {
  414.   while(n--)
  415.     *(tgt++)=(*(m1++))*(*(m2++));
  416. }
  417.  
  418. int pred(float *in,float *tgt,int n)
  419. {
  420.   int x,y;
  421.   float *p1,*p2;
  422.   double f0,f1,f2;
  423.   float temp;
  424.  
  425.   if(in[n]==0) return 0;
  426.   if((f0=*in)<=0) return 0;
  427.  
  428.   for(x=1;1;x++){
  429.     if (n<x) return 1;
  430.  
  431.     p1=in+x;
  432.     p2=tgt;
  433.     f1=*(p1--);
  434.     for(y=x;--y;) f1+=(*(p1--))*(*(p2++));
  435.  
  436.     p1=tgt+x-1;
  437.     p2=tgt;
  438.     *(p1--)=f2=-f1/f0;
  439.     for(y=x>>1;y--;) {
  440.       temp=*p2+*p1*f2;
  441.       *(p1--)+=*p2*f2;
  442.       *(p2++)=temp;
  443.     }
  444.     if((f0+=f1*f2)<0) return 0;
  445.   }
  446. }
  447.  
  448. co(int n,int i,int j,float *in,float *out,float *st1,float *st2,float
  449. *table)
  450. {
  451.   int a,b,c;
  452.   unsigned int x;
  453.   float *fp,*fp2;
  454.   float buffer1[37];
  455.   float buffer2[37];
  456.   float work[111];
  457.  
  458.   /* rotate and multiply */
  459.   c=(b=(a=n+i)+j)-i;
  460.   fp=st1+i;
  461.   for(x=0;x<b;x++) {
  462.     if (x==c) fp=in;
  463.     work[x]=*(table++)*(*(st1++)=*(fp++));
  464.   }
  465.   
  466.   prodsum(buffer1,work+n,i,n);
  467.   prodsum(buffer2,work+a,j,n);
  468.  
  469.   for(x=0;x<=n;x++) {
  470.     *st2=*st2*(0.5625)+buffer1[x];
  471.     out[x]=*(st2++)+buffer2[x];
  472.   }
  473.   *out*=1.00390625; /* to prevent clipping */
  474. }
  475.  
  476. /* product sum (lsf) */
  477. prodsum(float *tgt,float *src,int len,int n)
  478. {
  479.   unsigned int x;
  480.   float *p1,*p2;
  481.   double sum;
  482.  
  483.   while(n>=0)
  484.   {
  485.     sum=0;
  486.     p1=(p2=src)-n;
  487.     for(x=len;x--;) sum+=(*p1++)*(*p2++);
  488.     tgt[n--]=sum;
  489.   }
  490. }
  491.  
  492.