diff options
| -rw-r--r-- | big.c | 22 |
1 files changed, 14 insertions, 8 deletions
@@ -117,17 +117,17 @@ word bigplus(word x, word y) } /* ignore input signs, treat x,y as positive */ -word big_plus(x, y, signbit) -word x, y; -int signbit; +word big_plus(word x, word y, int signbit) { word d = digit0(x) + digit0(y); - word carry = ((d & IBASE) != 0); word r = make(INT, signbit | d & MAXDIGIT, 0); /* result */ word *z = &rest(r); /* pointer to rest of result */ + + word carry = ((d & IBASE) != 0); x = rest(x); y = rest(y); - while (x && y) { /* this loop has been unwrapped once, see above */ + + while (x && y) { d = carry + digit(x) + digit(y); carry = ((d & IBASE) != 0); *z = make(INT, d & MAXDIGIT, 0); @@ -135,8 +135,11 @@ int signbit; y = rest(y); z = &rest(*z); } - if (y) + + if (y) { x = y; /* by convention x is the longer one */ + } + while (x) { d = carry + digit(x); carry = ((d & IBASE) != 0); @@ -144,9 +147,12 @@ int signbit; x = rest(x); z = &rest(*z); } - if (carry) + + if (carry) { *z = make(INT, 1, 0); - return (r); + } + + return r; } word bigsub(x, y) |