On Wed, May 14, 2025 at 9:22 AM liuhongt <hongtao....@intel.com> wrote:
>
> The Intel Decimal Floating-Point Math Library is available as open-source on
> Netlib[1].
>
> [1] https://www.netlib.org/misc/intel/
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ready push to trunk.
>
> libgcc/config/libbid/ChangeLog:
>
> * bid128_string.c (MIN_DIGITS): New macro.
> (bid128_from_string): Update function.
Will adjust changelog to
libgcc/config/libbid/ChangeLog:
* bid128_string.c (MIN_DIGITS): New macro.
(bid128_from_string): Bug fix. Conversion from very long input
string to decimal.
> ---
> libgcc/config/libbid/bid128_string.c | 121 +++++++++++++++------------
> 1 file changed, 68 insertions(+), 53 deletions(-)
> mode change 100644 => 100755 libgcc/config/libbid/bid128_string.c
>
> diff --git a/libgcc/config/libbid/bid128_string.c
> b/libgcc/config/libbid/bid128_string.c
> old mode 100644
> new mode 100755
> index fce036ad5f8..49ad1795efb
> --- a/libgcc/config/libbid/bid128_string.c
> +++ b/libgcc/config/libbid/bid128_string.c
> @@ -31,6 +31,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively.
> If not, see
> #include "bid128_2_str.h"
> #include "bid128_2_str_macros.h"
>
> +#define MIN_DIGITS(a,b) ((a) < (b) ? (a) : (b))
> +
> extern int bid128_coeff_2_string (UINT64 X_hi, UINT64 X_lo,
> char *char_ptr);
>
> @@ -283,6 +285,7 @@ bid128_from_string (char *ps _RND_MODE_PARAM
> _EXC_FLAGS_PARAM
> int ndigits_before, ndigits_after, ndigits_total, dec_expon, sgn_exp,
> i, d2, rdx_pt_enc;
> char c, buffer[MAX_STRING_DIGITS_128];
> + int min_digits, sticky_bit=0;
> int save_rnd_mode;
> int save_fpsf;
>
> @@ -443,8 +446,10 @@ bid128_from_string (char *ps _RND_MODE_PARAM
> _EXC_FLAGS_PARAM
> if (!rdx_pt_enc) {
> // investigate string (before radix point)
> while ((unsigned) (c - '0') <= 9
> - && ndigits_before < MAX_STRING_DIGITS_128) {
> - buffer[ndigits_before] = c;
> + /*&& ndigits_before < MAX_STRING_DIGITS_128*/) {
> + if(ndigits_before < MAX_FORMAT_DIGITS_128) buffer[ndigits_before] = c;
> + else if(ndigits_before < MAX_STRING_DIGITS_128) {
> buffer[ndigits_before] = c; }
> + else if(c>'0') { sticky_bit = 1; }
> ps++;
> c = *ps;
> ndigits_before++;
> @@ -457,8 +462,10 @@ bid128_from_string (char *ps _RND_MODE_PARAM
> _EXC_FLAGS_PARAM
>
> // investigate string (after radix point)
> while ((unsigned) (c - '0') <= 9
> - && ndigits_total < MAX_STRING_DIGITS_128) {
> - buffer[ndigits_total] = c;
> + /*&& ndigits_total < MAX_STRING_DIGITS_128*/) {
> + if(ndigits_total < MAX_FORMAT_DIGITS_128) buffer[ndigits_total] =
> c;
> + else if(ndigits_total < MAX_STRING_DIGITS_128) {
> buffer[ndigits_total] = c; }
> + else if(c>'0') { sticky_bit = 1; }
> ps++;
> c = *ps;
> ndigits_total++;
> @@ -474,8 +481,10 @@ bid128_from_string (char *ps _RND_MODE_PARAM
> _EXC_FLAGS_PARAM
> ndigits_total = 0;
> // investigate string (after radix point)
> while ((unsigned) (c - '0') <= 9
> - && ndigits_total < MAX_STRING_DIGITS_128) {
> - buffer[ndigits_total] = c;
> + /*&& ndigits_total < MAX_STRING_DIGITS_128*/) {
> + if(ndigits_total < MAX_FORMAT_DIGITS_128) buffer[ndigits_total] = c;
> + else if(ndigits_total < MAX_STRING_DIGITS_128) {
> buffer[ndigits_total] = c; }
> + else if(c>'0') { sticky_bit = 1; }
> ps++;
> c = *ps;
> ndigits_total++;
> @@ -594,57 +603,63 @@ bid128_from_string (char *ps _RND_MODE_PARAM
> _EXC_FLAGS_PARAM
> coeff_l2 = coeff_low + coeff_low;
> coeff_low = (coeff_l2 << 2) + coeff_l2 + buffer[i] - '0';
> }
> - switch(rnd_mode) {
> - case ROUNDING_TO_NEAREST:
> - carry = ((unsigned) ('4' - buffer[i])) >> 31;
> - if ((buffer[i] == '5' && !(coeff_low & 1)) || dec_expon < 0) {
> - if (dec_expon >= 0) {
> - carry = 0;
> - i++;
> - }
> - for (; i < ndigits_total; i++) {
> - if (buffer[i] > '0') {
> - carry = 1;
> - break;
> - }
> + switch(rnd_mode) {
> + case ROUNDING_TO_NEAREST:
> + carry = ((unsigned) ('4' - buffer[i])) >> 31;
> + if ((buffer[i] == '5' && !(coeff_low & 1) && !sticky_bit) || dec_expon
> < 0) {
> + if (dec_expon >= 0) {
> + carry = 0;
> + i++;
> + }
> + min_digits = MIN_DIGITS(ndigits_total, MAX_STRING_DIGITS_128);
> + for (carry=sticky_bit; (!carry) && (i < min_digits); i++) {
> + if (buffer[i] > '0') {
> + carry = 1;
> + break;
> + }
> + }
> }
> - }
> - break;
> -
> - case ROUNDING_DOWN:
> - if(sign_x)
> - for (; i < ndigits_total; i++) {
> - if (buffer[i] > '0') {
> - carry = 1;
> - break;
> - }
> + break;
> +
> + case ROUNDING_DOWN:
> + if(sign_x) {
> + min_digits = MIN_DIGITS(ndigits_total, MAX_STRING_DIGITS_128);
> + for (carry=sticky_bit; (!carry) && (i < min_digits); i++) {
> + if (buffer[i] > '0') {
> + carry = 1;
> + break;
> + }
> + }
> }
> - break;
> - case ROUNDING_UP:
> - if(!sign_x)
> - for (; i < ndigits_total; i++) {
> - if (buffer[i] > '0') {
> - carry = 1;
> - break;
> - }
> + break;
> + case ROUNDING_UP:
> + if(!sign_x) {
> + min_digits = MIN_DIGITS(ndigits_total, MAX_STRING_DIGITS_128);
> + for (carry=sticky_bit; (!carry) && (i < min_digits); i++) {
> + if (buffer[i] > '0') {
> + carry = 1;
> + break;
> + }
> + }
> }
> - break;
> - case ROUNDING_TO_ZERO:
> - carry=0;
> - break;
> - case ROUNDING_TIES_AWAY:
> - carry = ((unsigned) ('4' - buffer[i])) >> 31;
> - if (dec_expon < 0) {
> - for (; i < ndigits_total; i++) {
> - if (buffer[i] > '0') {
> - carry = 1;
> - break;
> - }
> + break;
> + case ROUNDING_TO_ZERO:
> + carry=0;
> + break;
> + case ROUNDING_TIES_AWAY:
> + carry = ((unsigned) ('4' - buffer[i])) >> 31;
> + if (dec_expon < 0) {
> + min_digits = MIN_DIGITS(ndigits_total, MAX_STRING_DIGITS_128);
> + for (carry=sticky_bit; (!carry) && (i < min_digits); i++) {
> + if (buffer[i] > '0') {
> + carry = 1;
> + break;
> + }
> + }
> }
> - }
> - break;
> -
> - default: break; // default added to avoid compiler warning
> + break;
> +
> + default: break; // default added to avoid compiler warning
> }
> // now form the coefficient as coeff_high*10^17+coeff_low+carry
> scale_high = 100000000000000000ull;
> --
> 2.34.1
>
--
BR,
Hongtao
