From: Denys Vlasenko Date: Tue, 18 Dec 2018 11:23:16 +0000 (+0100) Subject: bc: replace signed division / 10 by unsigned X-Git-Tag: 1_30_0~123 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=e2e6ffd3c5e229ef386ca22e467c6553e570c55a;p=oweals%2Fbusybox.git bc: replace signed division / 10 by unsigned function old new delta zbc_num_a 443 441 -2 Signed-off-by: Denys Vlasenko --- 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; - } } }