Fix value comparison and sorting semantics

engine/lib/memory.c

@@ -61,6 +61,15 @@ PH7_PRIVATE void SyZero(void *pSrc, sxu32 nSize) {
 		zSrc++;
 	}
 }
+/*
+ * Byte comparison contract: SyMemcmp() returns the RAW delta of the first
+ * differing byte pair [unsigned bytes], in [-255,255], or 0 when the whole
+ * region is equal. It is NOT a 3-way ordering result: a delta such as
+ * 'a' - '{' = -26 collides with the engine error sentinels [SXERR_NOMATCH
+ * is -26, SXERR_ABORT is -10, ...]. Callers that need an ordering must
+ * reduce the delta to its sign [-1, 0, +1] before exposing it; see
+ * MemObjCmpString() in memobj.c and HashmapKeyBlobCmp() in hashmap.c.
+ */
 PH7_PRIVATE sxi32 SyMemcmp(const void *pB1, const void *pB2, sxu32 nSize) {
 	sxi32 rc;
 	if(nSize <= 0) {
@@ -712,6 +721,16 @@ PH7_PRIVATE sxi32 SyBlobDup(SyBlob *pSrc, SyBlob *pDest) {
 	}
 	return rc;
 }
+/*
+ * Blob ordering as implemented here: LENGTH BEFORE CONTENT. When the two
+ * lengths differ the shorter blob sorts first whatever the bytes hold (so
+ * "b" < "aa" is TRUE); the memcmp() pass only breaks equal-length ties.
+ * This is NOT a lexicographic 3-way contract — do not document or reuse it
+ * as one. Both verdicts are reduced to their sign [-1, 0, +1]: the raw
+ * SyMemcmp() delta can be any value in [-255, +255] and a delta such as
+ * -26 would collide with SXERR_NOMATCH, so this helper never hands out a
+ * raw delta.
+ */
 PH7_PRIVATE sxi32 SyBlobCmp(SyBlob *pLeft, SyBlob *pRight) {
 	sxi32 rc;
 	if(pLeft == 0 || pRight == 0) {
@@ -719,14 +738,14 @@ PH7_PRIVATE sxi32 SyBlobCmp(SyBlob *pLeft, SyBlob *pRight) {
 	}
 	if(pLeft->nByte != pRight->nByte) {
 		/* Length differ */
-		return pLeft->nByte - pRight->nByte;
+		return pLeft->nByte < pRight->nByte ? -1 : 1;
 	}
 	if(pLeft->nByte == 0) {
 		return 0;
 	}
 	/* Perform a standard memcmp() operation */
 	rc = SyMemcmp(pLeft->pBlob, pRight->pBlob, pLeft->nByte);
-	return rc;
+	return rc < 0 ? -1 : (rc > 0 ? 1 : 0);
 }
 PH7_PRIVATE sxi32 SyBlobReset(SyBlob *pBlob) {
 	pBlob->nByte = 0;