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//! a raised to integer power of b
//! ported from https://github.com/llvm-mirror/compiler-rt/blob/release_80/lib/builtins/powisf2.c
//! Multiplication order (left-to-right or right-to-left) does not matter for
//! error propagation and this method is optimized for performance, not accuracy.
const builtin = @import("builtin");
const common = @import("common.zig");
const std = @import("std");
pub const panic = common.panic;
comptime {
@export(&__powihf2, .{ .name = "__powihf2", .linkage = common.linkage, .visibility = common.visibility });
@export(&__powisf2, .{ .name = "__powisf2", .linkage = common.linkage, .visibility = common.visibility });
@export(&__powidf2, .{ .name = "__powidf2", .linkage = common.linkage, .visibility = common.visibility });
if (common.want_ppc_abi)
@export(&__powitf2, .{ .name = "__powikf2", .linkage = common.linkage, .visibility = common.visibility });
@export(&__powitf2, .{ .name = "__powitf2", .linkage = common.linkage, .visibility = common.visibility });
@export(&__powixf2, .{ .name = "__powixf2", .linkage = common.linkage, .visibility = common.visibility });
}
inline fn powiXf2(comptime FT: type, a: FT, b: i32) FT {
var x_a: FT = a;
var x_b: i32 = b;
const is_recip: bool = b < 0;
var r: FT = 1.0;
while (true) {
if (@as(u32, @bitCast(x_b)) & @as(u32, 1) != 0) {
r *= x_a;
}
x_b = @divTrunc(x_b, @as(i32, 2));
if (x_b == 0) break;
x_a *= x_a; // Multiplication of x_a propagates the error
}
return if (is_recip) 1 / r else r;
}
pub fn __powihf2(a: f16, b: i32) callconv(.c) f16 {
return powiXf2(f16, a, b);
}
pub fn __powisf2(a: f32, b: i32) callconv(.c) f32 {
return powiXf2(f32, a, b);
}
pub fn __powidf2(a: f64, b: i32) callconv(.c) f64 {
return powiXf2(f64, a, b);
}
pub fn __powitf2(a: f128, b: i32) callconv(.c) f128 {
return powiXf2(f128, a, b);
}
pub fn __powixf2(a: f80, b: i32) callconv(.c) f80 {
return powiXf2(f80, a, b);
}
test {
_ = @import("powiXf2_test.zig");
}
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