American spelling, aligned declarations. Resources a directory lists but the game's files lack count as absent, as with Sierra's interpreter.

agi.h

@@ -464,6 +464,7 @@ bool        agiQuirk(AgiQuirkE quirk);
 void        agiResClose(AgiGameT *game);
 uint8_t    *agiResLoad(const AgiGameT *game, AgiResTypeE type, uint16_t index, uint16_t *outLength);
 bool        agiResOpen(AgiGameT *game);
+bool        agiResPresent(const AgiGameT *game, AgiResTypeE type, uint16_t index);
 uint16_t    agiWordMatch(const AgiGameT *game, const char *text, uint8_t *outLen);
 
 

agiRes.c

@@ -64,6 +64,7 @@ static uint16_t    detectVersion(void);
 static void        loadDirectory(AgiGameT *game, const char *fileName, AgiResTypeE type);
 static uint8_t    *loadFile(const char *name, uint16_t maxBytes, uint16_t *outLength);
 static bool        loadObjects(AgiGameT *game);
+static bool        resHeaderRead(const AgiGameT *game, AgiResTypeE type, uint16_t index, uint8_t *header);
 
 
 // ----- Tables -----
@@ -237,6 +238,38 @@ static bool loadObjects(AgiGameT *game) {
 }
 
 
+// Seek to resource index's header in its VOL file and read it: false when
+// the number is past its directory or unused, or its entry names a VOL file
+// the game lacks or a place in one that holds no header for that volume
+// (12 34, then the entry's own volume). A directory can list a resource its
+// VOL files do not hold -- King's Quest 1's sounds 34 to 37 point past the
+// end of VOL.2, Space Quest 1's sound 0 into a VOL.15 -- which Sierra's
+// interpreter, reading a resource only when a script loads it, meets only
+// then.
+static bool resHeaderRead(const AgiGameT *game, AgiResTypeE type, uint16_t index, uint8_t *header) {
+    const AgiResEntryT  *entry;
+    FILE                *fp;
+    long                 offset;
+
+    if (index >= game->resCount[type]) {
+        return false;
+    }
+    entry = &game->resDir[type][index];
+    if (entry->volume >= AGI_MAX_VOLUMES) {
+        return false;
+    }
+    fp = game->volFiles[entry->volume];
+    if (fp == NULL) {
+        return false;
+    }
+    offset = ((long)entry->offsetHigh << DIR_OFFSET_HIGH_SHIFT) | (long)entry->offsetLow;
+    if (fseek(fp, offset, SEEK_SET) != 0 || fread(header, 1, VOL_HEADER_BYTES, fp) != VOL_HEADER_BYTES) {
+        return false;
+    }
+    return header[0] == VOL_SIG_0 && header[1] == VOL_SIG_1 && (header[2] & VOL_VOLUME_MASK) == entry->volume;
+}
+
+
 // ----- Public API (alphabetical) -----
 
 // Undo Sierra's XOR with "Avis Durgan" (OBJECT, and LOGIC messages from
@@ -297,38 +330,19 @@ void agiResClose(AgiGameT *game) {
 
 
 uint8_t *agiResLoad(const AgiGameT *game, AgiResTypeE type, uint16_t index, uint16_t *outLength) {
-    const AgiResEntryT  *entry;
+    FILE     *fp;
-    FILE                *fp;
+    uint8_t   header[VOL_HEADER_BYTES];
-    uint8_t              header[VOL_HEADER_BYTES];
+    uint8_t  *payload;
-    uint8_t             *payload;
+    uint16_t  length;
-    uint16_t             length;
-    long                 offset;
 
-    if (index >= game->resCount[type]) {
+    if (!resHeaderRead(game, type, index, header)) {
-        return NULL;
-    }
-    entry = &game->resDir[type][index];
-    if (entry->volume >= AGI_MAX_VOLUMES) {
-        return NULL;
-    }
-    fp = game->volFiles[entry->volume];
-    if (fp == NULL) {
-        return NULL;
-    }
-    offset = ((long)entry->offsetHigh << DIR_OFFSET_HIGH_SHIFT) | (long)entry->offsetLow;
-    if (fseek(fp, offset, SEEK_SET) != 0) {
-        return NULL;
-    }
-    if (fread(header, 1, VOL_HEADER_BYTES, fp) != VOL_HEADER_BYTES) {
-        return NULL;
-    }
-    if (header[0] != VOL_SIG_0 || header[1] != VOL_SIG_1) {
         return NULL;
     }
     // v3 resources are LZW-compressed and flag it in the volume byte.
-    if ((header[2] & VOL_COMPRESSED) != 0u || (header[2] & VOL_VOLUME_MASK) != entry->volume) {
+    if ((header[2] & VOL_COMPRESSED) != 0u) {
         return NULL;
     }
+    fp     = game->volFiles[game->resDir[type][index].volume];
     length = (uint16_t)(header[3] | ((uint16_t)header[4] << 8));
     if (length == 0u) {
         return NULL;
@@ -389,6 +403,15 @@ bool agiResOpen(AgiGameT *game) {
 }
 
 
+// Whether resource index of type is in the game's files: its entry points at
+// a resource header in its VOL file (resHeaderRead).
+bool agiResPresent(const AgiGameT *game, AgiResTypeE type, uint16_t index) {
+    uint8_t header[VOL_HEADER_BYTES];
+
+    return resHeaderRead(game, type, index, header);
+}
+
+
 // Find the longest dictionary entry that starts `text` and ends at a word
 // boundary (the end of text or a space). Entries can hold several words
 // ("pick up"). text is lower case with single spaces. Returns the word's

tests/testResources.c

@@ -5,7 +5,10 @@
 // hashes, a view's loop and cel counts with a hash of its decoded cels, a
 // logic's code and message counts, a sound's note counts -- for
 // scripts/test-agi.sh to compare, and a summary line on stderr. Exits 1
-// when a resource is malformed.
+// when a resource is malformed. A directory entry with no resource in the
+// game's files (agiResPresent) is listed as absent, not malformed: Sierra's
+// interpreter reads a resource only when a script loads it, and shipped
+// games list some they do not hold (King's Quest 1's sounds 34 to 37).
 //
 // Run on the host (BLANK port) from a folder holding DATA/.
 
@@ -29,6 +32,10 @@
 #define MAX_CEL_PIXELS       (255u * 255u)
 
 
+// What the lines call each resource type, by AgiResTypeE.
+static const char *const kTypeNames[AGI_RES_COUNT] = { "logic", "picture", "view", "sound" };
+
+
 // ----- Prototypes -----
 
 static uint32_t  fnv(uint32_t hash, const uint8_t *p, uint32_t length);
@@ -185,6 +192,8 @@ int main(void) {
     uint8_t   *pixels;
     uint16_t   n;
     uint16_t   counts[AGI_RES_COUNT];
+    uint16_t   absent;
+    uint8_t    t;
     bool       ok;
 
     memset(&cfg, 0, sizeof(cfg));
@@ -209,26 +218,37 @@ int main(void) {
         return 1;
     }
     memset(counts, 0, sizeof(counts));
-    ok = true;
+    absent = 0u;
+    ok     = true;
     for (n = 0u; n < AGI_MAX_RESOURCES; n++) {
-        if (n < gAgi->game.resCount[AGI_RES_LOGIC] && gAgi->game.resDir[AGI_RES_LOGIC][n].volume < AGI_MAX_VOLUMES) {
+        for (t = 0u; t < AGI_RES_COUNT; t++) {
-            ok = testLogic(n) && ok;
+            if (n >= gAgi->game.resCount[t] || gAgi->game.resDir[t][n].volume >= AGI_MAX_VOLUMES) {
-            counts[AGI_RES_LOGIC]++;
+                continue;
-        }
+            }
-        if (n < gAgi->game.resCount[AGI_RES_PIC] && gAgi->game.resDir[AGI_RES_PIC][n].volume < AGI_MAX_VOLUMES) {
+            if (!agiResPresent(&gAgi->game, (AgiResTypeE)t, n)) {
-            ok = testPicture(n, visual, priority) && ok;
+                fprintf(stderr, "%s %u: listed, but not in the game's files\n", kTypeNames[t], (unsigned)n);
-            counts[AGI_RES_PIC]++;
+                printf("%s %u absent\n", kTypeNames[t], (unsigned)n);
-        }
+                absent++;
-        if (n < gAgi->game.resCount[AGI_RES_VIEW] && gAgi->game.resDir[AGI_RES_VIEW][n].volume < AGI_MAX_VOLUMES) {
+                continue;
-            ok = testView(n, pixels) && ok;
+            }
-            counts[AGI_RES_VIEW]++;
+            switch ((AgiResTypeE)t) {
-        }
+                case AGI_RES_LOGIC:
-        if (n < gAgi->game.resCount[AGI_RES_SOUND] && gAgi->game.resDir[AGI_RES_SOUND][n].volume < AGI_MAX_VOLUMES) {
+                    ok = testLogic(n) && ok;
-            ok = testSound(n) && ok;
+                    break;
-            counts[AGI_RES_SOUND]++;
+                case AGI_RES_PIC:
+                    ok = testPicture(n, visual, priority) && ok;
+                    break;
+                case AGI_RES_VIEW:
+                    ok = testView(n, pixels) && ok;
+                    break;
+                case AGI_RES_SOUND:
+                default:
+                    ok = testSound(n) && ok;
+                    break;
+            }
+            counts[t]++;
         }
     }
-    fprintf(stderr, "%u logics, %u pictures, %u views, %u sounds%s\n", (unsigned)counts[AGI_RES_LOGIC], (unsigned)counts[AGI_RES_PIC],
+    fprintf(stderr, "%u logics, %u pictures, %u views, %u sounds, %u absent%s\n", (unsigned)counts[AGI_RES_LOGIC], (unsigned)counts[AGI_RES_PIC], (unsigned)counts[AGI_RES_VIEW], (unsigned)counts[AGI_RES_SOUND], (unsigned)absent, ok ? "" : " -- MALFORMED (see above)");
-            (unsigned)counts[AGI_RES_VIEW], (unsigned)counts[AGI_RES_SOUND], ok ? "" : " -- MALFORMED (see above)");
     return ok ? 0 : 1;
 }