    const std = @import("std");

    pub inline fn __builtin_bswap16(val: u16) u16 {
        return @byteSwap(val);
    }
    pub inline fn __builtin_bswap32(val: u32) u32 {
        return @byteSwap(val);
    }
    pub inline fn __builtin_bswap64(val: u64) u64 {
        return @byteSwap(val);
    }

    pub inline fn __builtin_signbit(val: f64) c_int {
        return @boolToInt(std.math.signbit(val));
    }
    pub inline fn __builtin_signbitf(val: f32) c_int {
        return @boolToInt(std.math.signbit(val));
    }

    pub inline fn __builtin_popcount(val: c_uint) c_int {
        // popcount of a c_uint will never exceed the capacity of a c_int

        @setRuntimeSafety(false);
        return @bitCast(c_int, @as(c_uint, @popCount(val)));
    }
    pub inline fn __builtin_ctz(val: c_uint) c_int {
        // Returns the number of trailing 0-bits in val, starting at the least significant bit position.

        // In C if `val` is 0, the result is undefined; in zig it's the number of bits in a c_uint

        @setRuntimeSafety(false);
        return @bitCast(c_int, @as(c_uint, @ctz(val)));
    }
    pub inline fn __builtin_clz(val: c_uint) c_int {
        // Returns the number of leading 0-bits in x, starting at the most significant bit position.

        // In C if `val` is 0, the result is undefined; in zig it's the number of bits in a c_uint

        @setRuntimeSafety(false);
        return @bitCast(c_int, @as(c_uint, @clz(val)));
    }

    pub inline fn __builtin_sqrt(val: f64) f64 {
        return @sqrt(val);
    }
    pub inline fn __builtin_sqrtf(val: f32) f32 {
        return @sqrt(val);
    }

    pub inline fn __builtin_sin(val: f64) f64 {
        return @sin(val);
    }
    pub inline fn __builtin_sinf(val: f32) f32 {
        return @sin(val);
    }
    pub inline fn __builtin_cos(val: f64) f64 {
        return @cos(val);
    }
    pub inline fn __builtin_cosf(val: f32) f32 {
        return @cos(val);
    }

    pub inline fn __builtin_exp(val: f64) f64 {
        return @exp(val);
    }
    pub inline fn __builtin_expf(val: f32) f32 {
        return @exp(val);
    }
    pub inline fn __builtin_exp2(val: f64) f64 {
        return @exp2(val);
    }
    pub inline fn __builtin_exp2f(val: f32) f32 {
        return @exp2(val);
    }
    pub inline fn __builtin_log(val: f64) f64 {
        return @log(val);
    }
    pub inline fn __builtin_logf(val: f32) f32 {
        return @log(val);
    }
    pub inline fn __builtin_log2(val: f64) f64 {
        return @log2(val);
    }
    pub inline fn __builtin_log2f(val: f32) f32 {
        return @log2(val);
    }
    pub inline fn __builtin_log10(val: f64) f64 {
        return @log10(val);
    }
    pub inline fn __builtin_log10f(val: f32) f32 {
        return @log10(val);
    }

    // Standard C Library bug: The absolute value of the most negative integer remains negative.

    pub inline fn __builtin_abs(val: c_int) c_int {
        return std.math.absInt(val) catch std.math.minInt(c_int);
    }
    pub inline fn __builtin_fabs(val: f64) f64 {
        return @fabs(val);
    }
    pub inline fn __builtin_fabsf(val: f32) f32 {
        return @fabs(val);
    }

    pub inline fn __builtin_floor(val: f64) f64 {
        return @floor(val);
    }
    pub inline fn __builtin_floorf(val: f32) f32 {
        return @floor(val);
    }
    pub inline fn __builtin_ceil(val: f64) f64 {
        return @ceil(val);
    }
    pub inline fn __builtin_ceilf(val: f32) f32 {
        return @ceil(val);
    }
    pub inline fn __builtin_trunc(val: f64) f64 {
        return @trunc(val);
    }
    pub inline fn __builtin_truncf(val: f32) f32 {
        return @trunc(val);
    }
    pub inline fn __builtin_round(val: f64) f64 {
        return @round(val);
    }
    pub inline fn __builtin_roundf(val: f32) f32 {
        return @round(val);
    }

    pub inline fn __builtin_strlen(s: [*c]const u8) usize {
        return std.mem.sliceTo(s, 0).len;
    }
    pub inline fn __builtin_strcmp(s1: [*c]const u8, s2: [*c]const u8) c_int {
        return @as(c_int, std.cstr.cmp(s1, s2));
    }

    pub inline fn __builtin_object_size(ptr: ?*const anyopaque, ty: c_int) usize {
        _ = ptr;
        // clang semantics match gcc's: https://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html

        // If it is not possible to determine which objects ptr points to at compile time,

        // __builtin_object_size should return (size_t) -1 for type 0 or 1 and (size_t) 0

        // for type 2 or 3.

        if (ty == 0 or ty == 1) return @bitCast(usize, -@as(isize, 1));
        if (ty == 2 or ty == 3) return 0;
        unreachable;
    }

    pub inline fn __builtin___memset_chk(
        dst: ?*anyopaque,
        val: c_int,
        len: usize,
        remaining: usize,
    ) ?*anyopaque {
        if (len > remaining) @panic("std.c.builtins.memset_chk called with len > remaining");
        return __builtin_memset(dst, val, len);
    }

    pub inline fn __builtin_memset(dst: ?*anyopaque, val: c_int, len: usize) ?*anyopaque {
        const dst_cast = @ptrCast([*c]u8, dst);
        @memset(dst_cast, @bitCast(u8, @truncate(i8, val)), len);
        return dst;
    }

    pub inline fn __builtin___memcpy_chk(
        noalias dst: ?*anyopaque,
        noalias src: ?*const anyopaque,
        len: usize,
        remaining: usize,
    ) ?*anyopaque {
        if (len > remaining) @panic("std.c.builtins.memcpy_chk called with len > remaining");
        return __builtin_memcpy(dst, src, len);
    }

    pub inline fn __builtin_memcpy(
        noalias dst: ?*anyopaque,
        noalias src: ?*const anyopaque,
        len: usize,
    ) ?*anyopaque {
        const dst_cast = @ptrCast([*c]u8, dst);
        const src_cast = @ptrCast([*c]const u8, src);

        @memcpy(dst_cast, src_cast, len);
        return dst;
    }

    /// The return value of __builtin_expect is `expr`. `c` is the expected value
    /// of `expr` and is used as a hint to the compiler in C. Here it is unused.
    pub inline fn __builtin_expect(expr: c_long, c: c_long) c_long {
        _ = c;
        return expr;
    }

    /// returns a quiet NaN. Quiet NaNs have many representations; tagp is used to select one in an
    /// implementation-defined way.
    /// This implementation is based on the description for __builtin_nan provided in the GCC docs at
    /// https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005fnan
    /// Comment is reproduced below:
    /// Since ISO C99 defines this function in terms of strtod, which we do not implement, a description
    /// of the parsing is in order.
    /// The string is parsed as by strtol; that is, the base is recognized by leading ‘0’ or ‘0x’ prefixes.
    /// The number parsed is placed in the significand such that the least significant bit of the number is
    ///    at the least significant bit of the significand.
    /// The number is truncated to fit the significand field provided.
    /// The significand is forced to be a quiet NaN.
    ///
    /// If tagp contains any non-numeric characters, the function returns a NaN whose significand is zero.
    /// If tagp is empty, the function returns a NaN whose significand is zero.
    pub inline fn __builtin_nanf(tagp: []const u8) f32 {
        const parsed = std.fmt.parseUnsigned(c_ulong, tagp, 0) catch 0;
        const bits = @truncate(u23, parsed); // single-precision float trailing significand is 23 bits

        return @bitCast(f32, @as(u32, bits) | std.math.qnan_u32);
    }

    pub inline fn __builtin_huge_valf() f32 {
        return std.math.inf(f32);
    }

    pub inline fn __builtin_inff() f32 {
        return std.math.inf(f32);
    }

    pub inline fn __builtin_isnan(x: anytype) c_int {
        return @boolToInt(std.math.isNan(x));
    }

    pub inline fn __builtin_isinf(x: anytype) c_int {
        return @boolToInt(std.math.isInf(x));
    }

    /// Similar to isinf, except the return value is -1 for an argument of -Inf and 1 for an argument of +Inf.
    pub inline fn __builtin_isinf_sign(x: anytype) c_int {
        if (!std.math.isInf(x)) return 0;
        return if (std.math.isPositiveInf(x)) 1 else -1;
    }

    pub inline fn __has_builtin(func: anytype) c_int {
        _ = func;
        return @boolToInt(true);
    }

    pub inline fn __builtin_assume(cond: bool) void {
        if (!cond) unreachable;
    }

    pub inline fn __builtin_unreachable() noreturn {
        unreachable;
    }

    pub inline fn __builtin_constant_p(expr: anytype) c_int {
        _ = expr;
        return @boolToInt(false);
    }
    pub fn __builtin_mul_overflow(a: anytype, b: anytype, result: *@TypeOf(a, b)) c_int {
        return @boolToInt(@mulWithOverflow(@TypeOf(a, b), a, b, result));
    }

    // __builtin_alloca_with_align is not currently implemented.

    // It is used in a run-translated-c test and a test-translate-c test to ensure that non-implemented

    // builtins are correctly demoted. If you implement __builtin_alloca_with_align, please update the

    // run-translated-c test and the test-translate-c test to use a different non-implemented builtin.

    // pub fn __builtin_alloca_with_align(size: usize, alignment: usize) callconv(.Inline) *anyopaque {}