Commit efa39c5343e13a13e65210f55da5df23ee3feb3e | zig | Meg's Mirrors

author	Marc Tiehuis <marc@tiehu.is> 2018-05-10 22:26:26+12:00
committer	Marc Tiehuis <marc@tiehu.is> 2018-05-10 22:26:26+12:00
log	efa39c5343e13a13e65210f55da5df23ee3feb3e
tree	5bf359499baa56f4066165c135e382d3a9bb1f1e
parent	c3ddf5069e0fb0b728ce275410988ccec3ab7ce9

Fix bigint shift-right partial shift

2 files changed, 9 insertions(+), 1 deletions(-)

src
- bigint.cpp
test
- cases
  - math.zig

src/bigint.cpp+1-1

...	@@ -1425,7 +1425,7 @@ void bigint_shr(BigInt dest, const BigInt op1, const BigInt *op2) {	...	@@ -1425,7 +1425,7 @@ void bigint_shr(BigInt dest, const BigInt op1, const BigInt *op2) {
1425	uint64_t digit = op1_digits[op_digit_index];	1425	uint64_t digit = op1_digits[op_digit_index];
1426	size_t dest_digit_index = op_digit_index - digit_shift_count;	1426	size_t dest_digit_index = op_digit_index - digit_shift_count;
1427	dest->data.digits[dest_digit_index] = carry \| (digit >> leftover_shift_count);	1427	dest->data.digits[dest_digit_index] = carry \| (digit >> leftover_shift_count);
1428	carry = digit << leftover_shift_count;	1428	carry = digit << (64 - leftover_shift_count);
1429		1429
1430	if (dest_digit_index == 0) { break; }	1430	if (dest_digit_index == 0) { break; }
1431	op_digit_index -= 1;	1431	op_digit_index -= 1;

test/cases/math.zig+8

...	@@ -366,6 +366,14 @@ test "big number multi-limb shift and mask" {	...	@@ -366,6 +366,14 @@ test "big number multi-limb shift and mask" {
366	}	366	}
367	}	367	}
368		368
		369	test "big number multi-limb partial shift right" {
		370	comptime {
		371	var a = 0x1ffffffffeeeeeeee;
		372	a >>= 16;
		373	assert(a == 0x1ffffffffeeee);
		374	}
		375	}
		376
369	test "xor" {	377	test "xor" {
370	test_xor();	378	test_xor();
371	comptime test_xor();	379	comptime test_xor();