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| author | Paul Eggert <eggert@cs.ucla.edu> | 2018-08-31 00:25:07 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2018-08-31 00:28:58 -0700 |
| commit | db2fed3bdfb351c3283e481829ce687931d27a3d (patch) | |
| tree | 4f2674ec4f4fe450fd483132b9ddcca48f9eaf81 /src/bignum.c | |
| parent | a451c6ec12b7b024f347364becb10c49807513ed (diff) | |
| download | emacs-db2fed3bdfb351c3283e481829ce687931d27a3d.tar.gz emacs-db2fed3bdfb351c3283e481829ce687931d27a3d.tar.bz2 emacs-db2fed3bdfb351c3283e481829ce687931d27a3d.zip | |
Several fixes for formatting bignums
* src/bignum.c: Include stdlib.h, for abs.
(bignum_bufsize, bignum_to_c_string): New functions.
* src/bignum.c (bignum_to_string):
* src/print.c (print_vectorlike): Use them.
* src/editfns.c (styled_format): Instead of having a separate
buffer for sprintf (which does not work for bignums), just append
to the main buffer. When formatting bignums, add support for the
standard integer flags -, #, 0, + and space. Fix some comments.
Capitalize properly when formatting bignums with %X. Use
functions like c_isdigit rather than reinventing the wheel.
Simplify computation of excess precision.
* src/print.c: Do not include bignum.h; no longer needed.
(print_vectorlike): Avoid recalculating string length.
* test/src/editfns-tests.el (format-bignum):
Test some of the above fixes.
Diffstat (limited to 'src/bignum.c')
| -rw-r--r-- | src/bignum.c | 37 |
1 files changed, 30 insertions, 7 deletions
diff --git a/src/bignum.c b/src/bignum.c index 5dbfdb9319a..b18ceccb59d 100644 --- a/src/bignum.c +++ b/src/bignum.c @@ -23,6 +23,8 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */ #include "lisp.h" +#include <stdlib.h> + /* Return the value of the Lisp bignum N, as a double. */ double bignum_to_double (Lisp_Object n) @@ -223,18 +225,39 @@ bignum_to_uintmax (Lisp_Object x) return v; } -/* Convert NUM to a base-BASE Lisp string. */ +/* Yield an upper bound on the buffer size needed to contain a C + string representing the bignum NUM in base BASE. This includes any + preceding '-' and the terminating null. */ +ptrdiff_t +bignum_bufsize (Lisp_Object num, int base) +{ + return mpz_sizeinbase (XBIGNUM (num)->value, base) + 2; +} + +/* Store into BUF (of size SIZE) the value of NUM as a base-BASE string. + If BASE is negative, use upper-case digits in base -BASE. + Return the string's length. + SIZE must equal bignum_bufsize (NUM, abs (BASE)). */ +ptrdiff_t +bignum_to_c_string (char *buf, ptrdiff_t size, Lisp_Object num, int base) +{ + eassert (bignum_bufsize (num, abs (base)) == size); + mpz_get_str (buf, base, XBIGNUM (num)->value); + ptrdiff_t n = size - 2; + return !buf[n - 1] ? n - 1 : n + !!buf[n]; +} + +/* Convert NUM to a base-BASE Lisp string. + If BASE is negative, use upper-case digits in base -BASE. */ Lisp_Object bignum_to_string (Lisp_Object num, int base) { - ptrdiff_t n = mpz_sizeinbase (XBIGNUM (num)->value, base) - 1; + ptrdiff_t size = bignum_bufsize (num, abs (base)); USE_SAFE_ALLOCA; - char *str = SAFE_ALLOCA (n + 3); - mpz_get_str (str, base, XBIGNUM (num)->value); - while (str[n]) - n++; - Lisp_Object result = make_unibyte_string (str, n); + char *str = SAFE_ALLOCA (size); + ptrdiff_t len = bignum_to_c_string (str, size, num, base); + Lisp_Object result = make_unibyte_string (str, len); SAFE_FREE (); return result; } |