diff options
Diffstat (limited to 'bignum.c')
-rw-r--r-- | bignum.c | 133 |
1 files changed, 120 insertions, 13 deletions
@@ -222,7 +222,110 @@ rb_int2inum(n) return rb_int2big(n); } -#ifdef HAVE_LONG_LONG +#if SIZEOF_LONG % SIZEOF_BDIGITS != 0 +# error unexpected SIZEOF_LONG : SIZEOF_BDIGITS ratio +#endif + +/* + * buf is an array of long integers. + * buf is ordered from least significant word to most significant word. + * buf[0] is the least significant word and + * buf[num_longs-1] is the most significant word. + * This means words in buf is little endian. + * However each word in buf is native endian. + * (buf[i]&1) is the least significant bit and + * (buf[i]&(1<<(SIZEOF_LONG*CHAR_BIT-1))) is the most significant bit + * for each 0 <= i < num_longs. + * So buf is little endian at whole on a little endian machine. + * But buf is mixed endian on a big endian machine. + */ +void +rb_big_pack(VALUE val, unsigned long *buf, long num_longs) +{ + val = rb_to_int(val); + if (num_longs == 0) + return; + if (FIXNUM_P(val)) { + long i; + long tmp = FIX2LONG(val); + buf[0] = (unsigned long)tmp; + tmp = tmp < 0 ? ~0L : 0; + for (i = 1; i < num_longs; i++) + buf[i] = (unsigned long)tmp; + return; + } + else { + long len = RBIGNUM_LEN(val); + BDIGIT *ds = BDIGITS(val), *dend = ds + len; + long i, j; + for (i = 0; i < num_longs && ds < dend; i++) { + unsigned long l = 0; + for (j = 0; j < DIGSPERLONG && ds < dend; j++, ds++) { + l |= ((unsigned long)*ds << (j * BITSPERDIG)); + } + buf[i] = l; + } + for (; i < num_longs; i++) + buf[i] = 0; + if (RBIGNUM_NEGATIVE_P(val)) { + for (i = 0; i < num_longs; i++) { + buf[i] = ~buf[i]; + } + for (i = 0; i < num_longs; i++) { + buf[i]++; + if (buf[i] != 0) + return; + } + } + } +} + +/* See rb_big_pack comment for endianness of buf. */ +VALUE +rb_big_unpack(unsigned long *buf, long num_longs) +{ + while (2 <= num_longs) { + if (buf[num_longs-1] == 0 && (long)buf[num_longs-2] >= 0) + num_longs--; + else if (buf[num_longs-1] == ~0UL && (long)buf[num_longs-2] < 0) + num_longs--; + else + break; + } + if (num_longs == 0) + return INT2FIX(0); + else if (num_longs == 1) + return LONG2NUM((long)buf[0]); + else { + VALUE big; + BDIGIT *ds; + long len = num_longs * DIGSPERLONG; + long i; + big = bignew(len, 1); + ds = BDIGITS(big); + for (i = 0; i < num_longs; i++) { + unsigned long d = buf[i]; +#if SIZEOF_LONG == SIZEOF_BDIGITS + *ds++ = d; +#else + int j; + for (j = 0; j < DIGSPERLONG; j++) { + *ds++ = BIGLO(d); + d = BIGDN(d); + } +#endif + } + if ((long)buf[num_longs-1] < 0) { + get2comp(big); + RBIGNUM_SET_SIGN(big, 0); + } + return bignorm(big); + } +} + +#define QUAD_SIZE 8 + +#if SIZEOF_LONG_LONG == QUAD_SIZE && SIZEOF_BDIGITS*2 == SIZEOF_LONG_LONG void rb_quad_pack(buf, val) @@ -295,7 +398,19 @@ rb_quad_unpack(buf, sign) #else -#define QUAD_SIZE 8 +static int +quad_buf_complement(char *buf, size_t len) +{ + size_t i; + for (i = 0; i < len; i++) + buf[i] = ~buf[i]; + for (i = 0; i < len; i++) { + buf[i]++; + if (buf[i] != 0) + return 0; + } + return 1; +} void rb_quad_pack(buf, val) @@ -314,12 +429,8 @@ rb_quad_pack(buf, val) rb_raise(rb_eRangeError, "bignum too big to convert into `quad int'"); } memcpy(buf, (char*)BDIGITS(val), len); - if (!RBIGNUM(val)->sign) { - len = QUAD_SIZE; - while (len--) { - *buf = ~*buf; - buf++; - } + if (RBIGNUM_NEGATIVE_P(val)) { + quad_buf_complement(buf, QUAD_SIZE); } } @@ -334,14 +445,10 @@ rb_quad_unpack(buf, sign) memcpy((char*)BDIGITS(big), buf, QUAD_SIZE); if (sign && BNEG(buf)) { - long len = QUAD_SIZE; char *tmp = (char*)BDIGITS(big); RBIGNUM(big)->sign = 0; - while (len--) { - *tmp = ~*tmp; - tmp++; - } + quad_buf_complement(tmp, QUAD_SIZE); } return bignorm(big); |