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const std = @import("std");
const common = @import("./common.zig");
pub const panic = @import("common.zig").panic;
comptime {
@export(&__addosi4, .{ .name = "__addosi4", .linkage = common.linkage, .visibility = common.visibility });
@export(&__addodi4, .{ .name = "__addodi4", .linkage = common.linkage, .visibility = common.visibility });
@export(&__addoti4, .{ .name = "__addoti4", .linkage = common.linkage, .visibility = common.visibility });
}
// addo - add overflow
// * return a+%b.
// * return if a+b overflows => 1 else => 0
// - addoXi4_generic as default
inline fn addoXi4_generic(comptime ST: type, a: ST, b: ST, overflow: *c_int) ST {
@setRuntimeSafety(common.test_safety);
overflow.* = 0;
const sum: ST = a +% b;
// Hackers Delight: section Overflow Detection, subsection Signed Add/Subtract
// Let sum = a +% b == a + b + carry == wraparound addition.
// Overflow in a+b+carry occurs, iff a and b have opposite signs
// and the sign of a+b+carry is the same as a (or equivalently b).
// Slower routine: res = ~(a ^ b) & ((sum ^ a)
// Faster routine: res = (sum ^ a) & (sum ^ b)
// Overflow occurred, iff (res < 0)
if (((sum ^ a) & (sum ^ b)) < 0)
overflow.* = 1;
return sum;
}
pub fn __addosi4(a: i32, b: i32, overflow: *c_int) callconv(.c) i32 {
return addoXi4_generic(i32, a, b, overflow);
}
pub fn __addodi4(a: i64, b: i64, overflow: *c_int) callconv(.c) i64 {
return addoXi4_generic(i64, a, b, overflow);
}
pub fn __addoti4(a: i128, b: i128, overflow: *c_int) callconv(.c) i128 {
return addoXi4_generic(i128, a, b, overflow);
}
test {
_ = @import("addosi4_test.zig");
_ = @import("addodi4_test.zig");
_ = @import("addoti4_test.zig");
}
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