+ { ERROR, CORE, KA, KB, MC, XA, CA, JX, HX },
+ { CORE, CORE, KA, KB, MC, XA, CA, JX, HX },
+ { KA, KA, KA, KB, MC, XA, ERROR, ERROR, ERROR},
+ { KB, KB, KB, KB, MC, XA, ERROR, ERROR, ERROR},
+ { MC, MC, MC, MC, MC, XA, ERROR, ERROR, ERROR},
+ { XA, XA, XA, XA, XA, XA, ERROR, ERROR, ERROR},
+ { CA, CA, ERROR, ERROR, ERROR, ERROR, CA, ERROR, ERROR},
+ { JX, JX, ERROR, ERROR, ERROR, ERROR, ERROR, JX, HX },
+ { HX, HX, ERROR, ERROR, ERROR, ERROR, ERROR, HX, HX },
+ };
+
+ if (a->arch != b->arch || matrix[a->mach][b->mach] == ERROR)
+ return NULL;
+
+ return (a->mach == matrix[a->mach][b->mach]) ? a : b;