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"
39 lines
1.3 KiB
Zig
39 lines
1.3 KiB
Zig
const builtin = @import("builtin");
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// subo - subtract overflow
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// * return a-%b.
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// * return if a-b overflows => 1 else => 0
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// - suboXi4_generic as default
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inline fn suboXi4_generic(comptime ST: type, a: ST, b: ST, overflow: *c_int) ST {
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@setRuntimeSafety(builtin.is_test);
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overflow.* = 0;
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var sum: ST = a -% b;
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// Hackers Delight: section Overflow Detection, subsection Signed Add/Subtract
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// Let sum = a -% b == a - b - carry == wraparound subtraction.
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// Overflow in a-b-carry occurs, iff a and b have opposite signs
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// and the sign of a-b-carry is opposite of a (or equivalently same as b).
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// Faster routine: res = (a ^ b) & (sum ^ a)
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// Slower routine: res = (sum^a) & ~(sum^b)
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// Overflow occured, iff (res < 0)
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if (((a ^ b) & (sum ^ a)) < 0)
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overflow.* = 1;
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return sum;
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}
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pub fn __subosi4(a: i32, b: i32, overflow: *c_int) callconv(.C) i32 {
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return suboXi4_generic(i32, a, b, overflow);
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}
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pub fn __subodi4(a: i64, b: i64, overflow: *c_int) callconv(.C) i64 {
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return suboXi4_generic(i64, a, b, overflow);
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}
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pub fn __suboti4(a: i128, b: i128, overflow: *c_int) callconv(.C) i128 {
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return suboXi4_generic(i128, a, b, overflow);
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}
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test {
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_ = @import("subosi4_test.zig");
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_ = @import("subodi4_test.zig");
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_ = @import("suboti4_test.zig");
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}
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