ec95e00e28
stage2: change logic for detecting whether the main package is inside
the std package. Previously it relied on realpath() which is not portable.
This uses resolve() which is how imports already work.
* stage2: fix cleanup bug when creating Module
* flatten lib/std/special/* to lib/*
- this was motivated by making main_pkg_is_inside_std false for
compiler_rt & friends.
* rename "mini libc" to "universal libc"
82 lines
2.4 KiB
Zig
82 lines
2.4 KiB
Zig
const subo = @import("subo.zig");
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const std = @import("std");
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const testing = std.testing;
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const math = std.math;
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fn test__suboti4(a: i128, b: i128) !void {
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var result_ov: c_int = undefined;
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var expected_ov: c_int = undefined;
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var result = subo.__suboti4(a, b, &result_ov);
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var expected: i128 = simple_suboti4(a, b, &expected_ov);
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try testing.expectEqual(expected, result);
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try testing.expectEqual(expected_ov, result_ov);
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}
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// 2 cases on evaluating `a-b`:
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// 1. `a-b` may underflow, iff b>0 && a<0 and a-b < min <=> a<min+b
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// 2. `a-b` may overflow, iff b<0 && a>0 and a-b > max <=> a>max+b
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// `-b` evaluation may overflow, iff b==min, but this is handled by the hardware
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pub fn simple_suboti4(a: i128, b: i128, overflow: *c_int) i128 {
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overflow.* = 0;
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const min: i128 = math.minInt(i128);
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const max: i128 = math.maxInt(i128);
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if (((b > 0) and (a < min + b)) or
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((b < 0) and (a > max + b)))
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overflow.* = 1;
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return a -% b;
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}
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test "suboti3" {
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const min: i128 = math.minInt(i128);
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const max: i128 = math.maxInt(i128);
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var i: i128 = 1;
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while (i < max) : (i *|= 2) {
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try test__suboti4(i, i);
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try test__suboti4(-i, -i);
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try test__suboti4(i, -i);
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try test__suboti4(-i, i);
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}
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// edge cases
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// 0 - 0 = 0
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// MIN - MIN = 0
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// MAX - MAX = 0
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// 0 - MIN overflow
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// 0 - MAX = MIN+1
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// MIN - 0 = MIN
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// MAX - 0 = MAX
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// MIN - MAX overflow
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// MAX - MIN overflow
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try test__suboti4(0, 0);
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try test__suboti4(min, min);
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try test__suboti4(max, max);
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try test__suboti4(0, min);
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try test__suboti4(0, max);
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try test__suboti4(min, 0);
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try test__suboti4(max, 0);
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try test__suboti4(min, max);
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try test__suboti4(max, min);
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// derived edge cases
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// MIN+1 - MIN = 1
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// MAX-1 - MAX = -1
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// 1 - MIN overflow
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// -1 - MIN = MAX
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// -1 - MAX = MIN
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// +1 - MAX = MIN+2
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// MIN - 1 overflow
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// MIN - -1 = MIN+1
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// MAX - 1 = MAX-1
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// MAX - -1 overflow
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try test__suboti4(min + 1, min);
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try test__suboti4(max - 1, max);
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try test__suboti4(1, min);
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try test__suboti4(-1, min);
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try test__suboti4(-1, max);
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try test__suboti4(1, max);
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try test__suboti4(min, 1);
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try test__suboti4(min, -1);
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try test__suboti4(max, -1);
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try test__suboti4(max, 1);
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}
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