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Diffstat (limited to 'misc/cgo/gmp/gmp.go')
| -rw-r--r-- | misc/cgo/gmp/gmp.go | 371 |
1 files changed, 0 insertions, 371 deletions
diff --git a/misc/cgo/gmp/gmp.go b/misc/cgo/gmp/gmp.go deleted file mode 100644 index 7faa71b69..000000000 --- a/misc/cgo/gmp/gmp.go +++ /dev/null @@ -1,371 +0,0 @@ -// Copyright 2009 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -/* -An example of wrapping a C library in Go. This is the GNU -multiprecision library gmp's integer type mpz_t wrapped to look like -the Go package big's integer type Int. - -This is a syntactically valid Go program—it can be parsed with the Go -parser and processed by godoc—but it is not compiled directly by 6g. -Instead, a separate tool, cgo, processes it to produce three output -files. The first two, 6g.go and 6c.c, are a Go source file for 6g and -a C source file for 6c; both compile as part of the named package -(gmp, in this example). The third, gcc.c, is a C source file for gcc; -it compiles into a shared object (.so) that is dynamically linked into -any 6.out that imports the first two files. - -The stanza - - // #include <gmp.h> - import "C" - -is a signal to cgo. The doc comment on the import of "C" provides -additional context for the C file. Here it is just a single #include -but it could contain arbitrary C definitions to be imported and used. - -Cgo recognizes any use of a qualified identifier C.xxx and uses gcc to -find the definition of xxx. If xxx is a type, cgo replaces C.xxx with -a Go translation. C arithmetic types translate to precisely-sized Go -arithmetic types. A C struct translates to a Go struct, field by -field; unrepresentable fields are replaced with opaque byte arrays. A -C union translates into a struct containing the first union member and -perhaps additional padding. C arrays become Go arrays. C pointers -become Go pointers. C function pointers become Go's uintptr. -C void pointer's become Go's unsafe.Pointer. - -For example, mpz_t is defined in <gmp.h> as: - - typedef unsigned long int mp_limb_t; - - typedef struct - { - int _mp_alloc; - int _mp_size; - mp_limb_t *_mp_d; - } __mpz_struct; - - typedef __mpz_struct mpz_t[1]; - -Cgo generates: - - type _C_int int32 - type _C_mp_limb_t uint64 - type _C___mpz_struct struct { - _mp_alloc _C_int; - _mp_size _C_int; - _mp_d *_C_mp_limb_t; - } - type _C_mpz_t [1]_C___mpz_struct - -and then replaces each occurrence of a type C.xxx with _C_xxx. - -If xxx is data, cgo arranges for C.xxx to refer to the C variable, -with the type translated as described above. To do this, cgo must -introduce a Go variable that points at the C variable (the linker can -be told to initialize this pointer). For example, if the gmp library -provided - - mpz_t zero; - -then cgo would rewrite a reference to C.zero by introducing - - var _C_zero *C.mpz_t - -and then replacing all instances of C.zero with (*_C_zero). - -Cgo's most interesting translation is for functions. If xxx is a C -function, then cgo rewrites C.xxx into a new function _C_xxx that -calls the C xxx in a standard pthread. The new function translates -its arguments, calls xxx, and translates the return value. - -Translation of parameters and the return value follows the type -translation above except that arrays passed as parameters translate -explicitly in Go to pointers to arrays, as they do (implicitly) in C. - -Garbage collection is the big problem. It is fine for the Go world to -have pointers into the C world and to free those pointers when they -are no longer needed. To help, the Go code can define Go objects -holding the C pointers and use runtime.SetFinalizer on those Go objects. - -It is much more difficult for the C world to have pointers into the Go -world, because the Go garbage collector is unaware of the memory -allocated by C. The most important consideration is not to -constrain future implementations, so the rule is that Go code can -hand a Go pointer to C code but must separately arrange for -Go to hang on to a reference to the pointer until C is done with it. -*/ -package gmp - -// #include <gmp.h> -// #include <stdlib.h> -import "C" - -import ( - "os" - "unsafe" -) - -/* - * one of a kind - */ - -// An Int represents a signed multi-precision integer. -// The zero value for an Int represents the value 0. -type Int struct { - i C.mpz_t - init bool -} - -// NewInt returns a new Int initialized to x. -func NewInt(x int64) *Int { return new(Int).SetInt64(x) } - -// Int promises that the zero value is a 0, but in gmp -// the zero value is a crash. To bridge the gap, the -// init bool says whether this is a valid gmp value. -// doinit initializes z.i if it needs it. This is not inherent -// to FFI, just a mismatch between Go's convention of -// making zero values useful and gmp's decision not to. -func (z *Int) doinit() { - if z.init { - return - } - z.init = true - C.mpz_init(&z.i[0]) -} - -// Bytes returns z's representation as a big-endian byte array. -func (z *Int) Bytes() []byte { - b := make([]byte, (z.Len()+7)/8) - n := C.size_t(len(b)) - C.mpz_export(unsafe.Pointer(&b[0]), &n, 1, 1, 1, 0, &z.i[0]) - return b[0:n] -} - -// Len returns the length of z in bits. 0 is considered to have length 1. -func (z *Int) Len() int { - z.doinit() - return int(C.mpz_sizeinbase(&z.i[0], 2)) -} - -// Set sets z = x and returns z. -func (z *Int) Set(x *Int) *Int { - z.doinit() - C.mpz_set(&z.i[0], &x.i[0]) - return z -} - -// SetBytes interprets b as the bytes of a big-endian integer -// and sets z to that value. -func (z *Int) SetBytes(b []byte) *Int { - z.doinit() - if len(b) == 0 { - z.SetInt64(0) - } else { - C.mpz_import(&z.i[0], C.size_t(len(b)), 1, 1, 1, 0, unsafe.Pointer(&b[0])) - } - return z -} - -// SetInt64 sets z = x and returns z. -func (z *Int) SetInt64(x int64) *Int { - z.doinit() - // TODO(rsc): more work on 32-bit platforms - C.mpz_set_si(&z.i[0], C.long(x)) - return z -} - -// SetString interprets s as a number in the given base -// and sets z to that value. The base must be in the range [2,36]. -// SetString returns an error if s cannot be parsed or the base is invalid. -func (z *Int) SetString(s string, base int) os.Error { - z.doinit() - if base < 2 || base > 36 { - return os.EINVAL - } - p := C.CString(s) - defer C.free(unsafe.Pointer(p)) - if C.mpz_set_str(&z.i[0], p, C.int(base)) < 0 { - return os.EINVAL - } - return nil -} - -// String returns the decimal representation of z. -func (z *Int) String() string { - if z == nil { - return "nil" - } - z.doinit() - p := C.mpz_get_str(nil, 10, &z.i[0]) - s := C.GoString(p) - C.free(unsafe.Pointer(p)) - return s -} - -func (z *Int) destroy() { - if z.init { - C.mpz_clear(&z.i[0]) - } - z.init = false -} - - -/* - * arithmetic - */ - -// Add sets z = x + y and returns z. -func (z *Int) Add(x, y *Int) *Int { - x.doinit() - y.doinit() - z.doinit() - C.mpz_add(&z.i[0], &x.i[0], &y.i[0]) - return z -} - -// Sub sets z = x - y and returns z. -func (z *Int) Sub(x, y *Int) *Int { - x.doinit() - y.doinit() - z.doinit() - C.mpz_sub(&z.i[0], &x.i[0], &y.i[0]) - return z -} - -// Mul sets z = x * y and returns z. -func (z *Int) Mul(x, y *Int) *Int { - x.doinit() - y.doinit() - z.doinit() - C.mpz_mul(&z.i[0], &x.i[0], &y.i[0]) - return z -} - -// Div sets z = x / y, rounding toward zero, and returns z. -func (z *Int) Div(x, y *Int) *Int { - x.doinit() - y.doinit() - z.doinit() - C.mpz_tdiv_q(&z.i[0], &x.i[0], &y.i[0]) - return z -} - -// Mod sets z = x % y and returns z. -// Like the result of the Go % operator, z has the same sign as x. -func (z *Int) Mod(x, y *Int) *Int { - x.doinit() - y.doinit() - z.doinit() - C.mpz_tdiv_r(&z.i[0], &x.i[0], &y.i[0]) - return z -} - -// Lsh sets z = x << s and returns z. -func (z *Int) Lsh(x *Int, s uint) *Int { - x.doinit() - z.doinit() - C.mpz_mul_2exp(&z.i[0], &x.i[0], C.ulong(s)) - return z -} - -// Rsh sets z = x >> s and returns z. -func (z *Int) Rsh(x *Int, s uint) *Int { - x.doinit() - z.doinit() - C.mpz_div_2exp(&z.i[0], &x.i[0], C.ulong(s)) - return z -} - -// Exp sets z = x^y % m and returns z. -// If m == nil, Exp sets z = x^y. -func (z *Int) Exp(x, y, m *Int) *Int { - m.doinit() - x.doinit() - y.doinit() - z.doinit() - if m == nil { - C.mpz_pow_ui(&z.i[0], &x.i[0], C.mpz_get_ui(&y.i[0])) - } else { - C.mpz_powm(&z.i[0], &x.i[0], &y.i[0], &m.i[0]) - } - return z -} - -func (z *Int) Int64() int64 { - if !z.init { - return 0 - } - return int64(C.mpz_get_si(&z.i[0])) -} - - -// Neg sets z = -x and returns z. -func (z *Int) Neg(x *Int) *Int { - x.doinit() - z.doinit() - C.mpz_neg(&z.i[0], &x.i[0]) - return z -} - -// Abs sets z to the absolute value of x and returns z. -func (z *Int) Abs(x *Int) *Int { - x.doinit() - z.doinit() - C.mpz_abs(&z.i[0], &x.i[0]) - return z -} - - -/* - * functions without a clear receiver - */ - -// CmpInt compares x and y. The result is -// -// -1 if x < y -// 0 if x == y -// +1 if x > y -// -func CmpInt(x, y *Int) int { - x.doinit() - y.doinit() - switch cmp := C.mpz_cmp(&x.i[0], &y.i[0]); { - case cmp < 0: - return -1 - case cmp == 0: - return 0 - } - return +1 -} - -// DivModInt sets q = x / y and r = x % y. -func DivModInt(q, r, x, y *Int) { - q.doinit() - r.doinit() - x.doinit() - y.doinit() - C.mpz_tdiv_qr(&q.i[0], &r.i[0], &x.i[0], &y.i[0]) -} - -// GcdInt sets d to the greatest common divisor of a and b, -// which must be positive numbers. -// If x and y are not nil, GcdInt sets x and y such that d = a*x + b*y. -// If either a or b is not positive, GcdInt sets d = x = y = 0. -func GcdInt(d, x, y, a, b *Int) { - d.doinit() - x.doinit() - y.doinit() - a.doinit() - b.doinit() - C.mpz_gcdext(&d.i[0], &x.i[0], &y.i[0], &a.i[0], &b.i[0]) -} - -// ProbablyPrime performs n Miller-Rabin tests to check whether z is prime. -// If it returns true, z is prime with probability 1 - 1/4^n. -// If it returns false, z is not prime. -func (z *Int) ProbablyPrime(n int) bool { - z.doinit() - return int(C.mpz_probab_prime_p(&z.i[0], C.int(n))) > 0 -} |