ref: 77246bfe1b9f147b1b255e811fb8b2032c49dc9e
parent: 34d97453258079f514c3297f88663fc23ff6e080
author: Ori Bernstein <ori@eigenstate.org>
date: Sat Jul 13 21:37:36 EDT 2019
Fix crash with large shifts in bigint.
--- a/lib/std/bigint.myr
+++ b/lib/std/bigint.myr
@@ -945,18 +945,22 @@
off = (s : uint64) / 32
shift = (s : uint64) % 32
- /* blit over the base values */
- for var i = 0; i < a.dig.len - off; i++
- a.dig[i] = a.dig[i + off]
- ;;
- a.dig = a.dig[:a.dig.len - off]
-
- /* and shift over by the remainder */
- carry = 0
- for var i = a.dig.len; i > 0; i--
- t = ((a.dig[i - 1] : uint64))
- a.dig[i - 1] = (carry | (t >> shift): uint32)
- carry = t << (32 - shift)
+ if off > a.dig.len
+ a.dig = a.dig[:0]
+ else
+ /* blit over the base values */
+ for var i = 0; i < a.dig.len - off; i++
+ a.dig[i] = a.dig[i + off]
+ ;;
+ a.dig = a.dig[:a.dig.len - off]
+
+ /* and shift over by the remainder */
+ carry = 0
+ for var i = a.dig.len; i > 0; i--
+ t = ((a.dig[i - 1] : uint64))
+ a.dig[i - 1] = (carry | (t >> shift): uint32)
+ carry = t << (32 - shift)
+ ;;
;;
-> trim(a)
}
--- a/lib/std/test/bigint.myr
+++ b/lib/std/test/bigint.myr
@@ -21,6 +21,7 @@
[.name = "format-zero", .fn = fmtzero],
[.name = "division", .fn = smokediv],
[.name = "modulo", .fn = smokemod],
+ [.name = "shift", .fn = shiftoff],
[.name = "add-negatives", .fn = addneg],
[.name = "sub-negatives", .fn = subneg],
][:])
@@ -261,6 +262,13 @@
run(c, std.mk(`Sub (\
std.mk(`Val "-8"), \
std.mk(`Val "-8"))), \
+ "0")
+}
+
+const shiftoff = {c+ run(c, std.mk(`Shr ( \
+ std.mk(`Val "1"), \
+ std.mk(`Val "65"))), \
"0")
}