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refactor dec div

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Yuki Omoto 2023-04-09 03:52:17 +09:00
parent 219e72ff20
commit f57085da05
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GPG key ID: 9A7D6C91D5219717
1 changed files with 5 additions and 17 deletions
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22
crates/compiler/builtins/bitcode/src/dec.zig
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@ -656,9 +656,6 @@ fn div_u256_by_u128(numer: U256, denom: u128) U256 {
// 1 <= sr <= N_UTWORD_BITS - 1
var carry: u128 = 0;
const i128_max: i128 = 170141183460469231731687303715884105727;
const i128_min: i128 = -170141183460469231731687303715884105728;
const u128_max: u128 = 340282366920938463463374607431768211455;
while (sr > 0) {
// r:q = ((r:q) << 1) | carry
r.hi = (r.hi << 1) | (r.lo >> (N_UDWORD_BITS - 1));
@ -691,24 +688,15 @@ fn div_u256_by_u128(numer: U256, denom: u128) U256 {
//
// As an implementation of `as_u256`, we wrap a negative value around to the maximum value of U256.
var hi_i128: i128 = undefined;
if (hi > i128_max) {
var overflowed_amount: u128 = hi - @intCast(u128, i128_max) - 1;
var overflowed_amount_i128 = @intCast(i128, overflowed_amount);
hi_i128 = i128_min + overflowed_amount_i128;
} else {
hi_i128 = @intCast(i128, hi);
}
var s_i128: i128 = math.shr(i128, hi_i128, 127);
var s_i128_abs = math.absInt(s_i128) catch unreachable;
var s_u128 = math.shr(u128, hi, 127);
var s_hi: u128 = undefined;
var s_lo: u128 = undefined;
if (s_i128 < 0) {
s_hi = u128_max;
s_lo = u128_max - @intCast(u128, (s_i128_abs - 1));
if (s_u128 == 1) {
s_hi = math.maxInt(u128);
s_lo = math.maxInt(u128) - 2;
} else {
s_hi = 0;
s_lo = @intCast(u128, s_i128_abs);
s_lo = s_u128;
}
var s = .{
.hi = s_hi,