[git commit] bc: replace signed division / 10 by unsigned
Denys Vlasenko
vda.linux at googlemail.com
Tue Dec 18 11:23:16 UTC 2018
commit: https://git.busybox.net/busybox/commit/?id=e2e6ffd3c5e229ef386ca22e467c6553e570c55a
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master
function old new delta
zbc_num_a 443 441 -2
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
miscutils/bc.c | 93 ++++++++++++++++++++--------------------------------------
1 file changed, 32 insertions(+), 61 deletions(-)
diff --git a/miscutils/bc.c b/miscutils/bc.c
index eaab6cee6..6c63c1703 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -1466,9 +1466,10 @@ static void bc_num_subArrays(BcDig *restrict a, BcDig *restrict b,
{
size_t i, j;
for (i = 0; i < len; ++i) {
- for (a[i] -= b[i], j = 0; a[i + j] < 0;) {
- a[i + j++] += 10;
- a[i + j] -= 1;
+ a[i] -= b[i];
+ for (j = i; a[j] < 0;) {
+ a[j++] += 10;
+ a[j] -= 1;
}
}
}
@@ -1647,7 +1648,7 @@ static FAST_FUNC BC_STATUS zbc_num_a(BcNum *a, BcNum *b, BcNum *restrict c, size
{
BcDig *ptr, *ptr_a, *ptr_b, *ptr_c;
size_t i, max, min_rdx, min_int, diff, a_int, b_int;
- int carry, in;
+ unsigned carry;
// Because this function doesn't need to use scale (per the bc spec),
// I am hijacking it to say whether it's doing an add or a subtract.
@@ -1672,15 +1673,16 @@ static FAST_FUNC BC_STATUS zbc_num_a(BcNum *a, BcNum *b, BcNum *restrict c, size
ptr = a->num;
ptr_a = a->num + diff;
ptr_b = b->num;
- }
- else {
+ } else {
diff = b->rdx - a->rdx;
ptr = b->num;
ptr_a = a->num;
ptr_b = b->num + diff;
}
- for (ptr_c = c->num, i = 0; i < diff; ++i, ++c->len) ptr_c[i] = ptr[i];
+ ptr_c = c->num;
+ for (i = 0; i < diff; ++i, ++c->len)
+ ptr_c[i] = ptr[i];
ptr_c += diff;
a_int = BC_NUM_INT(a);
@@ -1690,24 +1692,24 @@ static FAST_FUNC BC_STATUS zbc_num_a(BcNum *a, BcNum *b, BcNum *restrict c, size
min_int = b_int;
max = a_int;
ptr = ptr_a;
- }
- else {
+ } else {
min_int = a_int;
max = b_int;
ptr = ptr_b;
}
- for (carry = 0, i = 0; i < min_rdx + min_int; ++i, ++c->len) {
- in = ((int) ptr_a[i]) + ((int) ptr_b[i]) + carry;
+ carry = 0;
+ for (i = 0; i < min_rdx + min_int; ++i) {
+ unsigned in = (unsigned)ptr_a[i] + (unsigned)ptr_b[i] + carry;
carry = in / 10;
ptr_c[i] = (BcDig)(in % 10);
}
-
- for (; i < max + min_rdx; ++i, ++c->len) {
- in = ((int) ptr[i]) + carry;
+ for (; i < max + min_rdx; ++i) {
+ unsigned in = (unsigned)ptr[i] + carry;
carry = in / 10;
ptr_c[i] = (BcDig)(in % 10);
}
+ c->len += i;
if (carry != 0) c->num[c->len++] = (BcDig) carry;
@@ -1751,8 +1753,7 @@ static FAST_FUNC BC_STATUS zbc_num_s(BcNum *a, BcNum *b, BcNum *restrict c, size
neg = a->neg;
minuend = a;
subtrahend = b;
- }
- else {
+ } else {
neg = b->neg;
if (sub) neg = !neg;
minuend = b;
@@ -1765,8 +1766,7 @@ static FAST_FUNC BC_STATUS zbc_num_s(BcNum *a, BcNum *b, BcNum *restrict c, size
if (c->rdx < subtrahend->rdx) {
bc_num_extend(c, subtrahend->rdx - c->rdx);
start = 0;
- }
- else
+ } else
start = c->rdx - subtrahend->rdx;
bc_num_subArrays(c->num + start, subtrahend->num, subtrahend->len);
@@ -1795,11 +1795,11 @@ static FAST_FUNC BC_STATUS zbc_num_k(BcNum *restrict a, BcNum *restrict b,
RETURN_STATUS(BC_STATUS_SUCCESS);
}
- if (a->len + b->len < BC_NUM_KARATSUBA_LEN ||
- a->len < BC_NUM_KARATSUBA_LEN || b->len < BC_NUM_KARATSUBA_LEN)
- {
+ if (a->len + b->len < BC_NUM_KARATSUBA_LEN
+ || a->len < BC_NUM_KARATSUBA_LEN
+ || b->len < BC_NUM_KARATSUBA_LEN
+ ) {
size_t i, j, len;
- unsigned carry;
bc_num_expand(c, a->len + b->len + 1);
@@ -1807,11 +1807,10 @@ static FAST_FUNC BC_STATUS zbc_num_k(BcNum *restrict a, BcNum *restrict b,
c->len = len = 0;
for (i = 0; i < b->len; ++i) {
-
- carry = 0;
+ unsigned carry = 0;
for (j = 0; j < a->len; ++j) {
unsigned in = c->num[i + j];
- in += ((unsigned) a->num[j]) * ((unsigned) b->num[i]) + carry;
+ in += (unsigned)a->num[j] * (unsigned)b->num[i] + carry;
// note: compilers prefer _unsigned_ div/const
carry = in / 10;
c->num[i + j] = (BcDig)(in % 10);
@@ -2158,8 +2157,7 @@ static BC_STATUS zbc_num_binary(BcNum *a, BcNum *b, BcNum *c, size_t scale,
ptr_a = &num2;
memcpy(ptr_a, c, sizeof(BcNum));
init = true;
- }
- else
+ } else
ptr_a = a;
if (c == b) {
@@ -2168,8 +2166,7 @@ static BC_STATUS zbc_num_binary(BcNum *a, BcNum *b, BcNum *c, size_t scale,
memcpy(ptr_b, c, sizeof(BcNum));
init = true;
}
- }
- else
+ } else
ptr_b = b;
if (init)
@@ -2350,10 +2347,9 @@ static BC_STATUS zbc_num_sqrt(BcNum *a, BcNum *restrict b, size_t scale)
if (a->len == 0) {
bc_num_setToZero(b, scale);
RETURN_STATUS(BC_STATUS_SUCCESS);
- }
- else if (a->neg)
+ } else if (a->neg) {
RETURN_STATUS(bc_error("negative number"));
- else if (BC_NUM_ONE(a)) {
+ } else if (BC_NUM_ONE(a)) {
bc_num_one(b);
bc_num_extend(b, scale);
RETURN_STATUS(BC_STATUS_SUCCESS);
@@ -2380,7 +2376,6 @@ static BC_STATUS zbc_num_sqrt(BcNum *a, BcNum *restrict b, size_t scale)
pow = BC_NUM_INT(a);
if (pow) {
-
if (pow & 1)
x0->num[0] = 2;
else
@@ -2399,7 +2394,6 @@ static BC_STATUS zbc_num_sqrt(BcNum *a, BcNum *restrict b, size_t scale)
len = BC_NUM_INT(x0) + resrdx - 1;
while (cmp != 0 || digs < len) {
-
s = zbc_num_div(a, x0, &f, resrdx);
if (s) goto err;
s = zbc_num_add(x0, &f, &fprime, resrdx);
@@ -2429,8 +2423,7 @@ static BC_STATUS zbc_num_sqrt(BcNum *a, BcNum *restrict b, size_t scale)
bc_num_copy(b, x0);
scale -= 1;
if (b->rdx > scale) bc_num_truncate(b, b->rdx - scale);
-
-err:
+ err:
bc_num_free(&fprime);
bc_num_free(&f);
bc_num_free(&half);
@@ -2453,8 +2446,7 @@ static BC_STATUS zbc_num_divmod(BcNum *a, BcNum *b, BcNum *c, BcNum *d,
ptr_a = &num2;
bc_num_init(c, len);
init = true;
- }
- else {
+ } else {
ptr_a = a;
bc_num_expand(c, len);
}
@@ -2495,7 +2487,6 @@ static BC_STATUS zbc_num_modexp(BcNum *a, BcNum *b, BcNum *c, BcNum *restrict d)
bc_num_copy(&exp, b);
while (exp.len != 0) {
-
s = zbc_num_divmod(&exp, &two, &exp, &temp, 0);
if (s) goto err;
@@ -2511,8 +2502,7 @@ static BC_STATUS zbc_num_modexp(BcNum *a, BcNum *b, BcNum *c, BcNum *restrict d)
s = zbc_num_rem(&temp, c, &base, 0);
if (s) goto err;
}
-
-err:
+ err:
bc_num_free(&temp);
bc_num_free(&two);
bc_num_free(&exp);
@@ -2579,8 +2569,7 @@ static void bc_array_expand(BcVec *a, size_t len)
bc_num_init_DEF_SIZE(&data.n);
bc_vec_push(a, &data.n);
}
- }
- else {
+ } else {
while (len > a->len) {
bc_array_init(&data.v, true);
bc_vec_push(a, &data.v);
@@ -2614,33 +2603,24 @@ static void bc_result_copy(BcResult *d, BcResult *src)
d->t = src->t;
switch (d->t) {
-
case BC_RESULT_TEMP:
case BC_RESULT_IBASE:
case BC_RESULT_SCALE:
case BC_RESULT_OBASE:
- {
bc_num_init(&d->d.n, src->d.n.len);
bc_num_copy(&d->d.n, &src->d.n);
break;
- }
-
case BC_RESULT_VAR:
case BC_RESULT_ARRAY:
case BC_RESULT_ARRAY_ELEM:
- {
d->d.id.name = xstrdup(src->d.id.name);
break;
- }
-
case BC_RESULT_CONSTANT:
case BC_RESULT_LAST:
case BC_RESULT_ONE:
case BC_RESULT_STR:
- {
memcpy(&d->d.n, &src->d.n, sizeof(BcNum));
break;
- }
}
}
#endif // ENABLE_DC
@@ -2650,29 +2630,20 @@ static FAST_FUNC void bc_result_free(void *result)
BcResult *r = (BcResult *) result;
switch (r->t) {
-
case BC_RESULT_TEMP:
case BC_RESULT_IBASE:
case BC_RESULT_SCALE:
case BC_RESULT_OBASE:
- {
bc_num_free(&r->d.n);
break;
- }
-
case BC_RESULT_VAR:
case BC_RESULT_ARRAY:
case BC_RESULT_ARRAY_ELEM:
- {
free(r->d.id.name);
break;
- }
-
default:
- {
// Do nothing.
break;
- }
}
}
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