+bool
+couldDestroyCarry (asmop *aop)
+{
+ if (aop)
+ {
+ if (aop->type == AOP_EXSTK || aop->type == AOP_IY)
+ {
+ return TRUE;
+ }
+ }
+ return FALSE;
+}
+
+static void
+shiftIntoPair (int idx, asmop *aop)
+{
+ PAIR_ID id;
+
+ wassertl (IS_Z80, "Only implemented for the Z80");
+ // wassertl (aop->type == AOP_EXSTK, "Only implemented for EXSTK");
+
+ switch (idx)
+ {
+ case 0:
+ id = PAIR_HL;
+ break;
+ case 1:
+ id = PAIR_DE;
+ _push (PAIR_DE);
+ break;
+ default:
+ wassertl (0, "Internal error - hit default case");
+ }
+
+ emitDebug ("; Shift into pair idx %u", idx);
+
+ if (id == PAIR_HL)
+ {
+ setupPair (PAIR_HL, aop, 0);
+ }
+ else
+ {
+ setupPair (PAIR_IY, aop, 0);
+ emit2 ("push iy");
+ emit2 ("pop %s", _pairs[id].name);
+ }
+
+ aop->type = AOP_PAIRPTR;
+ aop->aopu.aop_pairId = id;
+ _G.pairs[id].offset = 0;
+ _G.pairs[id].last_type = aop->type;
+}
+
+static void
+setupToPreserveCarry (asmop *result, asmop *left, asmop *right)
+{
+ wassert (left && right);
+
+ if (IS_Z80)
+ {
+ if (couldDestroyCarry (right) && couldDestroyCarry (result))
+ {
+ shiftIntoPair (0, right);
+ shiftIntoPair (1, result);
+ }
+ else if (couldDestroyCarry (right))
+ {
+ shiftIntoPair (0, right);
+ }
+ else if (couldDestroyCarry (result))
+ {
+ shiftIntoPair (0, result);
+ }
+ else
+ {
+ /* Fine */
+ }
+ }
+}
+