mirror of
https://github.com/ziglang/zig.git
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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"
83 lines
2.4 KiB
Zig
83 lines
2.4 KiB
Zig
const subo = @import("subo.zig");
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const testing = @import("std").testing;
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fn test__subosi4(a: i32, b: i32) !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.__subosi4(a, b, &result_ov);
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var expected: i32 = simple_subosi4(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_subosi4(a: i32, b: i32, overflow: *c_int) i32 {
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overflow.* = 0;
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const min: i32 = -2147483648;
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const max: i32 = 2147483647;
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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 "subosi3" {
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// -2^31 <= i32 <= 2^31-1
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// 2^31 = 2147483648
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// 2^31-1 = 2147483647
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const min: i32 = -2147483648;
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const max: i32 = 2147483647;
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var i: i32 = 1;
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while (i < max) : (i *|= 2) {
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try test__subosi4(i, i);
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try test__subosi4(-i, -i);
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try test__subosi4(i, -i);
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try test__subosi4(-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__subosi4(0, 0);
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try test__subosi4(min, min);
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try test__subosi4(max, max);
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try test__subosi4(0, min);
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try test__subosi4(0, max);
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try test__subosi4(min, 0);
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try test__subosi4(max, 0);
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try test__subosi4(min, max);
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try test__subosi4(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__subosi4(min + 1, min);
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try test__subosi4(max - 1, max);
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try test__subosi4(1, min);
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try test__subosi4(-1, min);
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try test__subosi4(-1, max);
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try test__subosi4(1, max);
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try test__subosi4(min, 1);
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try test__subosi4(min, -1);
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try test__subosi4(max, -1);
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try test__subosi4(max, 1);
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}
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