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Annotation of tme/libtme/runlength.c, revision 1.1

1.1     ! root        1: /* $Id: runlength.c,v 1.1 2010/02/07 14:07:25 fredette Exp $ */
        !             2: 
        !             3: /* libtme/runlength.c - run length: */
        !             4: 
        !             5: /*
        !             6:  * Copyright (c) 2010 Matt Fredette
        !             7:  * All rights reserved.
        !             8:  *
        !             9:  * Redistribution and use in source and binary forms, with or without
        !            10:  * modification, are permitted provided that the following conditions
        !            11:  * are met:
        !            12:  * 1. Redistributions of source code must retain the above copyright
        !            13:  *    notice, this list of conditions and the following disclaimer.
        !            14:  * 2. Redistributions in binary form must reproduce the above copyright
        !            15:  *    notice, this list of conditions and the following disclaimer in the
        !            16:  *    documentation and/or other materials provided with the distribution.
        !            17:  * 3. All advertising materials mentioning features or use of this software
        !            18:  *    must display the following acknowledgement:
        !            19:  *      This product includes software developed by Matt Fredette.
        !            20:  * 4. The name of the author may not be used to endorse or promote products
        !            21:  *    derived from this software without specific prior written permission.
        !            22:  *
        !            23:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
        !            24:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
        !            25:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
        !            26:  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
        !            27:  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
        !            28:  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
        !            29:  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            30:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
        !            31:  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
        !            32:  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
        !            33:  * POSSIBILITY OF SUCH DAMAGE.
        !            34:  */
        !            35: 
        !            36: #include <tme/common.h>
        !            37: _TME_RCSID("$Id: runlength.c,v 1.1 2010/02/07 14:07:25 fredette Exp $");
        !            38: 
        !            39: /* includes: */
        !            40: #include <tme/runlength.h>
        !            41: #include <tme/misc.h>
        !            42: 
        !            43: /* this initializes runlength state: */
        !            44: void
        !            45: tme_runlength_init(struct tme_runlength *runlength)
        !            46: {
        !            47:   unsigned long runlength_history_count;
        !            48:   tme_runlength_t runlength_value;
        !            49: 
        !            50:   /* allocate the runlength history: */
        !            51:   runlength_history_count = runlength->tme_runlength_history_count;
        !            52:   assert (runlength_history_count > 0);
        !            53:   runlength->_tme_runlength_history = tme_new(tme_runlength_t, runlength_history_count);
        !            54: 
        !            55:   /* set the initial runlength history sum: */
        !            56:   runlength_value = runlength->tme_runlength_value;
        !            57:   runlength->_tme_runlength_history_sum
        !            58:     = (((double) runlength_value)
        !            59:        * runlength->tme_runlength_history_count);
        !            60:   
        !            61:   /* initialize the runlength history: */
        !            62:   do {
        !            63:     runlength->_tme_runlength_history[runlength_history_count - 1] = runlength_value;
        !            64:   } while (--runlength_history_count);
        !            65:   runlength->_tme_runlength_history_next = 0;
        !            66: }
        !            67: 
        !            68: /* this sets the runlength cycles target: */
        !            69: void
        !            70: tme_runlength_target_cycles(struct tme_runlength *runlength,
        !            71:                            union tme_value64 cycles_elapsed_target_value64)
        !            72: {
        !            73:   double two_to_the_thirtysecond;
        !            74: 
        !            75:   /* make 2^32: */
        !            76:   two_to_the_thirtysecond = 65536 * (double) 65536;
        !            77: 
        !            78:   /* set the target number of cycles to elapse during a run: */
        !            79:   runlength->_tme_runlength_cycles_elapsed_target
        !            80:     = ((cycles_elapsed_target_value64.tme_value64_uint32_hi
        !            81:        * two_to_the_thirtysecond)
        !            82:        + cycles_elapsed_target_value64.tme_value64_uint32_lo);
        !            83: }
        !            84: 
        !            85: /* this updates the runlength: */
        !            86: void
        !            87: tme_runlength_update(struct tme_runlength *runlength)
        !            88: {
        !            89:   double two_to_the_thirtysecond;
        !            90:   union tme_value64 cycles_elapsed;
        !            91:   tme_runlength_t runlength_value;
        !            92:   unsigned long runlength_history_next;
        !            93:   double runlength_history_sum;
        !            94: 
        !            95:   /* make 2^32: */
        !            96:   two_to_the_thirtysecond =  65536 * (double) 65536;
        !            97: 
        !            98:   /* get the number of cycles that elapsed during this run: */
        !            99:   cycles_elapsed = tme_misc_cycles();
        !           100:   (void) tme_value64_sub(&cycles_elapsed, &runlength->tme_runlength_cycles_start);
        !           101: 
        !           102:   /* get a better length for this run: */
        !           103:   runlength_value
        !           104:     = (runlength->tme_runlength_value
        !           105:        * (runlength->_tme_runlength_cycles_elapsed_target
        !           106:          / ((cycles_elapsed.tme_value64_uint32_hi
        !           107:              * two_to_the_thirtysecond)
        !           108:             + cycles_elapsed.tme_value64_uint32_lo)));
        !           109:   if (__tme_predict_false(runlength_value == 0)) {
        !           110:     runlength_value += 1;
        !           111:   }
        !           112: 
        !           113:   /* update the runlength history and sum: */
        !           114:   runlength_history_next = runlength->_tme_runlength_history_next;
        !           115:   runlength_history_sum
        !           116:     = ((runlength->_tme_runlength_history_sum
        !           117:        - runlength->_tme_runlength_history[runlength_history_next])
        !           118:        + runlength_value);
        !           119:   runlength->_tme_runlength_history[runlength_history_next] = runlength_value;
        !           120:   runlength->_tme_runlength_history_sum = runlength_history_sum;
        !           121:   if (runlength_history_next == 0) {
        !           122:     runlength_history_next = runlength->tme_runlength_history_count;
        !           123:   }
        !           124:   runlength->_tme_runlength_history_next = runlength_history_next - 1;
        !           125: 
        !           126:   /* update the runlength value: */
        !           127:   runlength->tme_runlength_value
        !           128:     = (runlength_history_sum
        !           129:        / runlength->tme_runlength_history_count);
        !           130: }

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