bigint: Add prototypes for immediate add+sub.

core/math/bigint/basic.odin

@@ -21,7 +21,7 @@ import "core:intrinsics"
 /*
 	High-level addition. Handles sign.
 */
-add :: proc(dest, a, b: ^Int) -> (err: Error) {
+add_two_ints :: proc(dest, a, b: ^Int) -> (err: Error) {
 	dest := dest; x := a; y := b;
 	_panic_if_uninitialized(a); _panic_if_uninitialized(b); _panic_if_uninitialized(dest);
 
@@ -46,10 +46,23 @@ add :: proc(dest, a, b: ^Int) -> (err: Error) {
 	return _sub(dest, x, y);
 }
 
+/*
+	Adds the unsigned `DIGIT` immediate to an `Int`,
+	such that the `DIGIT` doesn't have to be turned into an `Int` first.
+
+	dest = a + digit;
+*/
+add_digit :: proc(dest, a: ^int, digit: DIGIT) -> (err: Error) {
+
+	return .Unimplemented;
+}
+
+add :: proc{add_two_ints, add_digit};
+
 /*
 	High-level subtraction, dest = number - decrease. Handles signs.
 */
-sub :: proc(dest, number, decrease: ^Int) -> (err: Error) {
+sub_two_ints :: proc(dest, number, decrease: ^Int) -> (err: Error) {
 	dest := dest; x := number; y := decrease;
 	_panic_if_uninitialized(number); _panic_if_uninitialized(decrease); _panic_if_uninitialized(dest);
 
@@ -83,6 +96,19 @@ sub :: proc(dest, number, decrease: ^Int) -> (err: Error) {
 	return _sub(dest, x, y);
 }
 
+/*
+	Adds the unsigned `DIGIT` immediate to an `Int`,
+	such that the `DIGIT` doesn't have to be turned into an `Int` first.
+
+	dest = number - decrease;
+*/
+sub_digit :: proc(dest, number: ^int, decrease: DIGIT) -> (err: Error) {
+
+	return .Unimplemented;
+}
+
+sub :: proc{sub_two_ints, sub_digit};
+
 /*
 	==========================
 		Low-level routines