82 lines
2.2 KiB
Zig
82 lines
2.2 KiB
Zig
const assert = @import("debug.zig").assert;
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pub const Cmp = enum {
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Equal,
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Greater,
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Less,
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};
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pub fn min(x: var, y: var) -> @typeOf(x + y) {
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if (x < y) x else y
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}
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pub fn max(x: var, y: var) -> @typeOf(x + y) {
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if (x > y) x else y
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}
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error Overflow;
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pub fn mulOverflow(comptime T: type, a: T, b: T) -> %T {
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var answer: T = undefined;
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if (@mulWithOverflow(T, a, b, &answer)) error.Overflow else answer
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}
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pub fn addOverflow(comptime T: type, a: T, b: T) -> %T {
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var answer: T = undefined;
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if (@addWithOverflow(T, a, b, &answer)) error.Overflow else answer
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}
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pub fn subOverflow(comptime T: type, a: T, b: T) -> %T {
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var answer: T = undefined;
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if (@subWithOverflow(T, a, b, &answer)) error.Overflow else answer
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}
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pub fn shlOverflow(comptime T: type, a: T, b: T) -> %T {
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var answer: T = undefined;
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if (@shlWithOverflow(T, a, b, &answer)) error.Overflow else answer
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}
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pub fn log(comptime base: usize, value: var) -> @typeOf(value) {
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const T = @typeOf(value);
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if (@isInteger(T)) {
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if (base == 2) {
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return T.bit_count - 1 - @clz(value);
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} else {
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@compileError("TODO implement log for non base 2 integers");
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}
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} else if (@isFloat(T)) {
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@compileError("TODO implement log for floats");
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} else {
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@compileError("log expects integer or float, found '" ++ @typeName(T) ++ "'");
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}
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}
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/// x must be an integer or a float
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/// Note that this causes undefined behavior if
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/// @typeOf(x).is_signed and x == @minValue(@typeOf(x)).
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pub fn abs(x: var) -> @typeOf(x) {
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const T = @typeOf(x);
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if (@isInteger(T)) {
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return if (x < 0) -x else x;
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} else if (@isFloat(T)) {
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@compileError("TODO implement abs for floats");
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} else {
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unreachable;
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}
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}
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fn getReturnTypeForAbs(comptime T: type) -> type {
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if (@isInteger(T)) {
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return @IntType(false, T.bit_count);
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} else {
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return T;
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}
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}
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test "testMath" {
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testMathImpl();
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comptime testMathImpl();
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}
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fn testMathImpl() {
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assert(%%mulOverflow(i32, 3, 4) == 12);
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assert(%%addOverflow(i32, 3, 4) == 7);
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assert(%%subOverflow(i32, 3, 4) == -1);
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assert(%%shlOverflow(i32, 0b11, 4) == 0b110000);
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}
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