Yukihiro "Matz" Matsumoto
ff0e20453f
Fixed three bugs that caused infinite loops in GCD calculations: 1. mpz_set_int() didn't shrink sz when setting a smaller value. mpz_realloc() only grows allocations, so setting a 1-limb value to an mpz_t with sz=3 would leave sz=3, breaking algorithms that depend on correct sz values. 2. mpz_set_uint64() had the same issue. 3. mpz_gcd() used mpz_init_set() which preserves the sign. GCD should work with absolute values since gcd(a,b) = gcd(|a|,|b|). With negative inputs, the sign would oscillate during mod operations, preventing the Euclidean algorithm from converging. 4. mpz_div_2exp() when e==0 and z==x would corrupt data by calling mpz_init_heap() which overwrites z->p before copying from x. These bugs were discovered via ClusterFuzz with complex rational number calculations. Co-authored-by: Claude <noreply@anthropic.com>
mruby-bigint
mruby-bigint is an mrbgem that provides multi-precision integer (BigInt) support for mruby. It allows you to work with integers that are larger than the standard Integer type can handle.
This extension uses fgmp, which is a public domain implementation of a subset of the GNU gmp library by Mark Henderson markh@wimsey.bc.ca. But it's heavily modified to fit with mruby. You can get the original source code from https://github.com/deischi/fgmp.git. You can read the original README for fgmp in README-fgmp.md.
If you want to create your own Multi-precision Integer GEM, see examples/mrbgems/mruby-YOUR-bigint/TODO-HINT.md.
Features
- Basic arithmetic operations:
+,-,*,/,% - Power operation:
** - Modular exponentiation
- Bitwise operations:
&,|,^,<<,>> - Comparison:
<=> - Conversion to and from strings:
to_s,String#to_i(with base) - Square root
- Greatest Common Divisor (GCD) (available if
MRB_USE_RATIONALis defined)
Usage
Here are some simple examples of how to use mruby-bigint:
# Creating BigInts
a = BigInt(12345678901234567890)
b = "98765432109876543210".to_i(10) # Specify base 10 for string conversion
# Arithmetic operations
c = a + b
puts c.to_s # Output: 111111111011111111100
d = a * 2
puts d.to_s # Output: 24691357802469135780
# Comparison
puts a <=> b # Output: -1
fgmp Dependency
mruby-bigint depends on fgmp. For more information about fgmp, please see README-fgmp.md.