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Annotation of qemu/audio/rate_template.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * QEMU Mixing engine
        !             3:  *
        !             4:  * Copyright (c) 2004-2005 Vassili Karpov (malc)
        !             5:  * Copyright (c) 1998 Fabrice Bellard
        !             6:  *
        !             7:  * Permission is hereby granted, free of charge, to any person obtaining a copy
        !             8:  * of this software and associated documentation files (the "Software"), to deal
        !             9:  * in the Software without restriction, including without limitation the rights
        !            10:  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
        !            11:  * copies of the Software, and to permit persons to whom the Software is
        !            12:  * furnished to do so, subject to the following conditions:
        !            13:  *
        !            14:  * The above copyright notice and this permission notice shall be included in
        !            15:  * all copies or substantial portions of the Software.
        !            16:  *
        !            17:  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
        !            18:  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
        !            19:  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
        !            20:  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
        !            21:  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
        !            22:  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
        !            23:  * THE SOFTWARE.
        !            24:  */
        !            25: 
        !            26: /*
        !            27:  * Processed signed long samples from ibuf to obuf.
        !            28:  * Return number of samples processed.
        !            29:  */
        !            30: void NAME (void *opaque, st_sample_t *ibuf, st_sample_t *obuf,
        !            31:            int *isamp, int *osamp)
        !            32: {
        !            33:     struct rate *rate = opaque;
        !            34:     st_sample_t *istart, *iend;
        !            35:     st_sample_t *ostart, *oend;
        !            36:     st_sample_t ilast, icur, out;
        !            37: #ifdef FLOAT_MIXENG
        !            38:     real_t t;
        !            39: #else
        !            40:     int64_t t;
        !            41: #endif
        !            42: 
        !            43:     ilast = rate->ilast;
        !            44: 
        !            45:     istart = ibuf;
        !            46:     iend = ibuf + *isamp;
        !            47: 
        !            48:     ostart = obuf;
        !            49:     oend = obuf + *osamp;
        !            50: 
        !            51:     if (rate->opos_inc == (1ULL + UINT_MAX)) {
        !            52:         int i, n = *isamp > *osamp ? *osamp : *isamp;
        !            53:         for (i = 0; i < n; i++) {
        !            54:             OP (obuf[i].l, ibuf[i].r);
        !            55:             OP (obuf[i].r, ibuf[i].r);
        !            56:         }
        !            57:         *isamp = n;
        !            58:         *osamp = n;
        !            59:         return;
        !            60:     }
        !            61: 
        !            62:     while (obuf < oend) {
        !            63: 
        !            64:         /* Safety catch to make sure we have input samples.  */
        !            65:         if (ibuf >= iend) {
        !            66:             break;
        !            67:         }
        !            68: 
        !            69:         /* read as many input samples so that ipos > opos */
        !            70: 
        !            71:         while (rate->ipos <= (rate->opos >> 32)) {
        !            72:             ilast = *ibuf++;
        !            73:             rate->ipos++;
        !            74:             /* See if we finished the input buffer yet */
        !            75:             if (ibuf >= iend) {
        !            76:                 goto the_end;
        !            77:             }
        !            78:         }
        !            79: 
        !            80:         icur = *ibuf;
        !            81: 
        !            82:         /* interpolate */
        !            83: #ifdef FLOAT_MIXENG
        !            84: #ifdef RECIPROCAL
        !            85:         t = (rate->opos & UINT_MAX) * (1.f / UINT_MAX);
        !            86: #else
        !            87:         t = (rate->opos & UINT_MAX) / (real_t) UINT_MAX;
        !            88: #endif
        !            89:         out.l = (ilast.l * (1.0 - t)) + icur.l * t;
        !            90:         out.r = (ilast.r * (1.0 - t)) + icur.r * t;
        !            91: #else
        !            92:         t = rate->opos & 0xffffffff;
        !            93:         out.l = (ilast.l * ((int64_t) UINT_MAX - t) + icur.l * t) >> 32;
        !            94:         out.r = (ilast.r * ((int64_t) UINT_MAX - t) + icur.r * t) >> 32;
        !            95: #endif
        !            96: 
        !            97:         /* output sample & increment position */
        !            98:         OP (obuf->l, out.l);
        !            99:         OP (obuf->r, out.r);
        !           100:         obuf += 1;
        !           101:         rate->opos += rate->opos_inc;
        !           102:     }
        !           103: 
        !           104: the_end:
        !           105:     *isamp = ibuf - istart;
        !           106:     *osamp = obuf - ostart;
        !           107:     rate->ilast = ilast;
        !           108: }
        !           109: 
        !           110: #undef NAME
        !           111: #undef OP

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