prj/cam/libsrc/portal/oracle.c

   1 /*
   2 @Copyright Looking Glass Studios, Inc.
   3 1996,1997,1998,1999,2000 Unpublished Work.
   4 */
   5
   6 // $Header: r:/t2repos/thief2/libsrc/portold/oracle.c,v 1.1 1996/10/21 21:43:00 buzzard Exp $
   7
   8 // Oracle: can answer any question in O(1) time.
   9 //   It does this by cacheing the result from a previous frame
  10
  11 #include <lg.h>
  12 #include <string.h>
  13
  14 int oracle_flags;
  15 int oracle_save;
  16 int oracle_last_memorized;
  17
  18 uchar *current_memorize;
  19 uchar *last_memorize;
  20 int current_playback;
  21 int current_record, oracle_record_size;
  22
  23 // INVARIANT:   oracle_save != 0 iff current_memorize != 0
  24
  25 void OracleFinishQueues(void)
  26 {
  27    if (current_memorize) {
  28       if (last_memorize)
  29          Free(last_memorize);
  30       last_memorize = current_memorize;
  31       oracle_last_memorized = oracle_save;
  32
  33       current_memorize = 0;
  34       oracle_save = 0;
  35    }
  36 }
  37
  38 void OracleStartFrame(int answer_flags, int memorize_flags)
  39 {
  40    OracleFinishQueues();
  41
  42    if (answer_flags == oracle_last_memorized) {
  43       oracle_flags = answer_flags;
  44       current_playback = 0;
  45    } else
  46       oracle_flags = 0;
  47
  48    if (memorize_flags) {
  49       oracle_save = memorize_flags;
  50       oracle_record_size = 1024;
  51       current_memorize = Malloc(oracle_record_size);
  52       current_record = 0;
  53    }
  54 }
  55
  56 // make the oracle try to answer exactly this set of flags
  57 void OracleSmartStart(int answer_flags)
  58 {
  59    if (answer_flags == oracle_last_memorized)
  60       OracleStartFrame(answer_flags, 0);
  61    else if (answer_flags == oracle_save)
  62       OracleStartFrame(answer_flags, 0);
  63    else
  64       OracleStartFrame(0, answer_flags);
  65 }
  66
  67 bool OracleStore(void *data, int datasize)
  68 {
  69    while (current_record + datasize >= oracle_record_size) {
  70       oracle_record_size *= 2;
  71       current_memorize = Realloc(current_memorize, oracle_record_size);
  72    }
  73
  74    memcpy(current_memorize + current_record, data, datasize);
  75    current_record += datasize;
  76    return TRUE;
  77 }
  78
  79 bool OracleFetch(int requeue, void *data, int datasize)
  80 {
  81    memcpy(data, last_memorize + current_playback, datasize);
  82    current_playback += datasize;
  83    if (requeue)
  84       OracleStore(data, datasize);
  85    return TRUE;
  86 }
  87
  88 bool OracleFetchBool(int requeue)
  89 {
  90    bool result;
  91    OracleFetch(requeue, &result, sizeof(result));
  92    return result;
  93 }
  94
  95 bool OracleStoreBool(bool result)
  96 {
  97    OracleStore(&result, sizeof(result));
  98    return result;
  99 }
 100