diff options
Diffstat (limited to 'libf2c/libF77/qbitbits.c')
-rw-r--r-- | libf2c/libF77/qbitbits.c | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/libf2c/libF77/qbitbits.c b/libf2c/libF77/qbitbits.c new file mode 100644 index 0000000..f72858e --- /dev/null +++ b/libf2c/libF77/qbitbits.c @@ -0,0 +1,62 @@ +#include "f2c.h" + +#ifndef LONGBITS +#define LONGBITS 32 +#endif + +#ifndef LONG8BITS +#define LONG8BITS (2*LONGBITS) +#endif + +integer +qbit_bits (longint a, integer b, integer len) +{ + /* Assume 2's complement arithmetic */ + + ulongint x, y; + + x = (ulongint) a; + y = (ulongint) - 1L; + x >>= b; + y <<= len; + return (longint) (x & y); +} + +longint +qbit_cshift (longint a, integer b, integer len) +{ + ulongint x, y, z; + + x = (ulongint) a; + if (len <= 0) + { + if (len == 0) + return 0; + goto full_len; + } + if (len >= LONG8BITS) + { + full_len: + if (b >= 0) + { + b %= LONG8BITS; + return (longint) (x << b | x >> (LONG8BITS - b)); + } + b = -b; + b %= LONG8BITS; + return (longint) (x << (LONG8BITS - b) | x >> b); + } + y = z = (unsigned long) -1; + y <<= len; + z &= ~y; + y &= x; + x &= z; + if (b >= 0) + { + b %= len; + return (longint) (y | (z & (x << b | x >> (len - b)))); + } + b = -b; + b %= len; + return (longint) (y | (z & (x >> b | x << (len - b)))); +} |