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Annotation of tme/libtme/recode-conds.c, revision 1.1

1.1     ! root        1: /* $Id: recode-conds.c,v 1.2 2008/07/01 01:39:01 fredette Exp $ */
        !             2: 
        !             3: /* libtme/recode-conds.c - generic support for recode conditions: */
        !             4: 
        !             5: /*
        !             6:  * Copyright (c) 2008 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: recode-conds.c,v 1.2 2008/07/01 01:39:01 fredette Exp $");
        !            38: 
        !            39: #if TME_HAVE_RECODE
        !            40: 
        !            41: /* includes: */
        !            42: #include "recode-impl.h"
        !            43: 
        !            44: /* this returns a conditions thunk for a conditions group: */
        !            45: const struct tme_recode_conds_thunk *
        !            46: tme_recode_conds_thunk(struct tme_recode_ic *ic,
        !            47:                       const struct tme_recode_conds_group *conds_group_template)
        !            48: {
        !            49:   const struct tme_recode_conds_group *conds_group_other;
        !            50:   struct tme_recode_conds_group *conds_group;
        !            51: 
        !            52:   /* loop over the existing conditions groups: */
        !            53:   for (conds_group_other = ic->tme_recode_ic_conds_groups;
        !            54:        conds_group_other != NULL;
        !            55:        conds_group_other = conds_group_other->tme_recode_conds_group_next) {
        !            56: 
        !            57:     /* skip this existing conditions group if its flags register
        !            58:        size or index or flags don't match: */
        !            59:     if (conds_group_other->tme_recode_conds_group_flags_reg_size
        !            60:        != conds_group_template->tme_recode_conds_group_flags_reg_size) {
        !            61:       continue;
        !            62:     }
        !            63:     if (conds_group_other->tme_recode_conds_group_flags_reg
        !            64:        != conds_group_template->tme_recode_conds_group_flags_reg) {
        !            65:       continue;
        !            66:     }
        !            67:     if (conds_group_other->tme_recode_conds_group_flags
        !            68:        != conds_group_template->tme_recode_conds_group_flags) {
        !            69:       continue;
        !            70:     }
        !            71: 
        !            72:     /* skip this existing conditions group if its conditions count or
        !            73:        guest function don't match: */
        !            74:     if (conds_group_other->tme_recode_conds_group_cond_count
        !            75:        != conds_group_template->tme_recode_conds_group_cond_count) {
        !            76:       continue;
        !            77:     }
        !            78:     if (conds_group_other->tme_recode_conds_group_guest_func
        !            79:        != conds_group_template->tme_recode_conds_group_guest_func) {
        !            80:       continue;
        !            81:     }
        !            82: 
        !            83:     /* return the conditions thunk from the existing conditions
        !            84:        group: */
        !            85:     return (conds_group_other->tme_recode_conds_group_thunk);
        !            86:   }
        !            87: 
        !            88:   /* allocate and fill the new conditions group: */
        !            89:   conds_group = tme_new0(struct tme_recode_conds_group, 1);
        !            90:   *conds_group = *conds_group_template;
        !            91: 
        !            92:   /* build the new conditions thunk: */
        !            93:   conds_group->tme_recode_conds_group_thunk = tme_recode_host_conds_thunk_new(ic, conds_group);
        !            94: 
        !            95:   /* add this new conditions group to the ic: */
        !            96:   conds_group->tme_recode_conds_group_next = ic->tme_recode_ic_conds_groups;
        !            97:   ic->tme_recode_ic_conds_groups = conds_group;
        !            98: 
        !            99:   /* update the initial thunk offset of the first variable thunk: */
        !           100:   ic->tme_recode_ic_thunk_off_variable
        !           101:     = tme_recode_build_to_thunk_off(ic, ic->tme_recode_ic_thunk_build_next);
        !           102: 
        !           103:   /* return the conditions thunk: */
        !           104:   return (conds_group->tme_recode_conds_group_thunk);
        !           105: }
        !           106: 
        !           107: /* this generic function returns the maximum index for a conditions
        !           108:    group's flags: */
        !           109: tme_uint32_t
        !           110: tme_recode_conds_group_flags_index_max(const struct tme_recode_conds_group *conds_group)
        !           111: {
        !           112:   tme_recode_uguest_t conds_group_flags_mask;
        !           113:   unsigned int count_bits;
        !           114: 
        !           115:   /* count the number of bits in the condition group flags mask: */
        !           116:   conds_group_flags_mask = conds_group->tme_recode_conds_group_flags;
        !           117:   assert (conds_group_flags_mask != 0);
        !           118:   for (count_bits = 0;
        !           119:        conds_group_flags_mask != 0;
        !           120:        count_bits++) {
        !           121:     conds_group_flags_mask &= (conds_group_flags_mask - 1);
        !           122:   }
        !           123: 
        !           124:   /* return the maximum condition group flags index: */
        !           125:   assert (count_bits <= (sizeof(tme_uint32_t) * 8));
        !           126:   return ((((tme_uint32_t) 2) << (count_bits - 1)) - 1);
        !           127: }
        !           128: 
        !           129: /* this generic function returns the indexed combination of a
        !           130:    conditions group's flags: */
        !           131: tme_recode_uguest_t
        !           132: tme_recode_conds_group_flags_from_index(const struct tme_recode_conds_group *conds_group,
        !           133:                                       tme_uint32_t conds_group_flags_index)
        !           134: {
        !           135:   tme_recode_uguest_t conds_group_flags_mask;
        !           136:   tme_recode_uguest_t conds_group_flags;
        !           137:   tme_recode_uguest_t conds_group_flag_next;
        !           138: 
        !           139:   /* make this combination of the flags: */
        !           140:   conds_group_flags_mask = conds_group->tme_recode_conds_group_flags;
        !           141:   conds_group_flags = 0;
        !           142:   conds_group_flag_next = 1;
        !           143:   do {
        !           144:     if (conds_group_flags_mask & conds_group_flag_next) {
        !           145:       if (conds_group_flags_index & 1) {
        !           146:        conds_group_flags |= conds_group_flag_next;
        !           147:       }
        !           148:       conds_group_flags_index >>= 1;
        !           149:     }
        !           150:     conds_group_flag_next <<= 1;
        !           151:   } while (conds_group_flags_index != 0);
        !           152:   return (conds_group_flags);
        !           153: }
        !           154: 
        !           155: /* this generic function returns a simple mask of a conditions group's
        !           156:    flags and one or more bitwise operations that can be used with the
        !           157:    mask to test the given condition.  it returns zero if the condition
        !           158:    can't be tested with a simple mask: */
        !           159: tme_uint32_t
        !           160: tme_recode_conds_simple_mask(const struct tme_recode_conds_group *conds_group,
        !           161:                             tme_uint32_t cond,
        !           162:                             tme_recode_uguest_t *_conds_group_flags_mask)
        !           163: {
        !           164:   tme_recode_uguest_t conds_group_flags_same_for_mask[2];
        !           165:   int conds_group_flags_same_for_defined[2];
        !           166:   tme_uint32_t conds_group_flags_index;
        !           167:   tme_recode_uguest_t conds_group_flags;
        !           168:   int cond_true;
        !           169:   tme_recode_uguest_t conds_group_flags_same_for[2];
        !           170:   tme_recode_uguest_t conds_group_flags_mask;
        !           171:   tme_uint32_t bitwise_mask;
        !           172: 
        !           173:   /* we haven't seen any combination of flags that make the condition
        !           174:      either true or false yet: */
        !           175:   conds_group_flags_same_for_mask[1] = conds_group->tme_recode_conds_group_flags;
        !           176:   conds_group_flags_same_for_mask[0] = conds_group->tme_recode_conds_group_flags;
        !           177:   conds_group_flags_same_for_defined[1] = FALSE;
        !           178:   conds_group_flags_same_for_defined[0] = FALSE;
        !           179: 
        !           180:   /* loop over all combinations of the flags: */
        !           181:   conds_group_flags_index = tme_recode_conds_group_flags_index_max(conds_group);
        !           182:   do {
        !           183:     conds_group_flags = tme_recode_conds_group_flags_from_index(conds_group, conds_group_flags_index);
        !           184: 
        !           185:     /* test if this combination of flags makes the condition true: */
        !           186:     cond_true = ((*conds_group->tme_recode_conds_group_guest_func)(conds_group_flags, cond) != 0);
        !           187: 
        !           188:     /* if this is the first combination of flags that we have seen
        !           189:        that makes the condition have this state: */
        !           190:     if (!conds_group_flags_same_for_defined[cond_true]) {
        !           191: 
        !           192:       /* start tracking flags that always have the same values when
        !           193:         the condition has this state: */
        !           194:       conds_group_flags_same_for[cond_true] = conds_group_flags;
        !           195:       conds_group_flags_same_for_defined[cond_true] = TRUE;
        !           196:     }
        !           197: 
        !           198:     /* otherwise, this is not the first combination of flags that
        !           199:        we have seen that makes the condition have this state: */
        !           200:     else {
        !           201: 
        !           202:       /* drop any flags that before had the same value when the
        !           203:         condition had this state, that now have a different value
        !           204:         when the condition has this same state: */
        !           205:       conds_group_flags_same_for_mask[cond_true]
        !           206:        &= ~(conds_group_flags_same_for[cond_true]
        !           207:             ^ conds_group_flags);
        !           208:     }
        !           209: 
        !           210:   } while (conds_group_flags_index-- != 0);
        !           211: 
        !           212:   /* if we never saw a combination of flags that makes the condition
        !           213:      true: */
        !           214:   if (!conds_group_flags_same_for_defined[1]) {
        !           215: 
        !           216:     /* this condition is always false, which we can express with an
        !           217:        all-bits-zero mask and either OR or AND: */
        !           218:     *_conds_group_flags_mask = 0;
        !           219:     return (TME_RECODE_BITWISE_OR | TME_RECODE_BITWISE_AND);
        !           220:   }
        !           221: 
        !           222:   /* if we never saw a combination of flags that makes the condition
        !           223:      false: */
        !           224:   if (!conds_group_flags_same_for_defined[0]) {
        !           225: 
        !           226:     /* this condition is always true, which we can express with an
        !           227:        all-bits-zero mask and either NOR or NAND: */
        !           228:     *_conds_group_flags_mask = 0;
        !           229:     return (TME_RECODE_BITWISE_NOR | TME_RECODE_BITWISE_NAND);
        !           230:   }
        !           231: 
        !           232:   /* bits that are the same in all combinations of flags that make the
        !           233:      condition both true and false, can't be in the mask of flags that
        !           234:      determine the condition: */
        !           235:   conds_group_flags_mask
        !           236:     = ((conds_group_flags_same_for[1]
        !           237:        ^ ~conds_group_flags_same_for[0])
        !           238:        & conds_group_flags_same_for_mask[1]
        !           239:        & conds_group_flags_same_for_mask[0]);
        !           240:   conds_group_flags_same_for_mask[1] &= ~conds_group_flags_mask;
        !           241:   conds_group_flags_same_for_mask[0] &= ~conds_group_flags_mask;
        !           242: 
        !           243:   /* if there is any mask of flags that determine one state of the
        !           244:      condition, the mask of flags that determine the other state must
        !           245:      either be zero, or be exactly the same mask: */
        !           246:   conds_group_flags_mask = conds_group_flags_same_for_mask[1];
        !           247:   if (conds_group_flags_mask == 0) {
        !           248:     conds_group_flags_mask = conds_group_flags_same_for_mask[0];
        !           249:   }
        !           250:   else {
        !           251:     assert (conds_group_flags_same_for_mask[0] == 0
        !           252:            || conds_group_flags_same_for_mask[0] == conds_group_flags_mask);
        !           253:   }
        !           254: 
        !           255:   /* loop over all combinations of the flags again, eliminating
        !           256:      bitwise operations that don't give the correct condition state
        !           257:      under the mask for all combinations: */
        !           258:   bitwise_mask
        !           259:     = (TME_RECODE_BITWISE_OR
        !           260:        | TME_RECODE_BITWISE_NOR
        !           261:        | TME_RECODE_BITWISE_AND
        !           262:        | TME_RECODE_BITWISE_NAND);
        !           263:   conds_group_flags_index = tme_recode_conds_group_flags_index_max(conds_group);
        !           264:   do {
        !           265:     conds_group_flags = tme_recode_conds_group_flags_from_index(conds_group, conds_group_flags_index);
        !           266: 
        !           267:     /* test if this combination of flags makes the condition true: */
        !           268:     cond_true = ((*conds_group->tme_recode_conds_group_guest_func)(conds_group_flags, cond) != 0);
        !           269: 
        !           270:     /* mask off all other flags: */
        !           271:     conds_group_flags &= conds_group_flags_mask;
        !           272: 
        !           273:     /* eliminate bitwise operations that don't give the correct
        !           274:        condition state for the flags: */
        !           275:     if (cond_true != (conds_group_flags != 0)) {
        !           276:       bitwise_mask &= ~TME_RECODE_BITWISE_OR;
        !           277:     }
        !           278:     if (cond_true != (conds_group_flags == 0)) {
        !           279:       bitwise_mask &= ~TME_RECODE_BITWISE_NOR;
        !           280:     }
        !           281:     if (cond_true != (conds_group_flags == conds_group_flags_mask)) {
        !           282:       bitwise_mask &= ~TME_RECODE_BITWISE_AND;
        !           283:     }
        !           284:     if (cond_true != (conds_group_flags != conds_group_flags_mask)) {
        !           285:       bitwise_mask &= ~TME_RECODE_BITWISE_NAND;
        !           286:     }
        !           287: 
        !           288:   } while (conds_group_flags_index-- != 0);
        !           289: 
        !           290:   /* return any mask of flags and bitwise operations: */
        !           291:   *_conds_group_flags_mask = conds_group_flags_mask;
        !           292:   return (bitwise_mask);
        !           293: }
        !           294: 
        !           295: #ifdef TME_RECODE_DEBUG
        !           296: #include <stdio.h>
        !           297: 
        !           298: /* this function dumps a conditions thunk: */
        !           299: void
        !           300: tme_recode_conds_thunk_dump(const struct tme_recode_ic *ic,
        !           301:                            const struct tme_recode_conds_thunk *conds_thunk,
        !           302:                            const char * const *cond_names)
        !           303: {
        !           304:   printf("  flags offset: 0x%x\n  flags tested: ",
        !           305:         (unsigned int) conds_thunk->tme_recode_conds_thunk_flags_offset);
        !           306:   tme_recode_uguest_dump(conds_thunk->tme_recode_conds_thunk_flags);
        !           307:   printf("\n");
        !           308:   tme_recode_host_conds_thunk_dump(ic, conds_thunk, cond_names);
        !           309: }
        !           310: #endif /* TME_RECODE_DEBUG */
        !           311: 
        !           312: #endif /* TME_HAVE_RECODE */

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