+/* Implement "word-size + 1 bit" addition for
+ {resultP->X_extrabit:resultP->X_add_number} + {rhs_highbit:amount}. This
+ is used so that the full range of unsigned word values and the full range of
+ signed word values can be represented in an O_constant expression, which is
+ useful e.g. for .sleb128 directives. */
+
+void
+add_to_result (expressionS *resultP, offsetT amount, int rhs_highbit)
+{
+ valueT ures = resultP->X_add_number;
+ valueT uamount = amount;
+
+ resultP->X_add_number += amount;
+
+ resultP->X_extrabit ^= rhs_highbit;
+
+ if (ures + uamount < ures)
+ resultP->X_extrabit ^= 1;
+}
+
+/* Similarly, for subtraction. */
+
+void
+subtract_from_result (expressionS *resultP, offsetT amount, int rhs_highbit)
+{
+ valueT ures = resultP->X_add_number;
+ valueT uamount = amount;
+
+ resultP->X_add_number -= amount;
+
+ resultP->X_extrabit ^= rhs_highbit;
+
+ if (ures < uamount)
+ resultP->X_extrabit ^= 1;
+}
+