From 99c078bb6b1f3bbd3e81360982437650dcfedf1c Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Thu, 25 Jul 2024 16:01:16 +0900
Subject: [PATCH] mruby-bigint (mrb_bint_2comp): simplify using mpz_2comp()

---
 mrbgems/mruby-bigint/core/bigint.c  | 34 +++++------------------------
 mrbgems/mruby-sprintf/src/sprintf.c | 11 +++++++---
 2 files changed, 13 insertions(+), 32 deletions(-)

diff --git a/mrbgems/mruby-bigint/core/bigint.c b/mrbgems/mruby-bigint/core/bigint.c
index 187309724..458269476 100644
--- a/mrbgems/mruby-bigint/core/bigint.c
+++ b/mrbgems/mruby-bigint/core/bigint.c
@@ -1776,40 +1776,16 @@ mrb_bint_hash(mrb_state *mrb, mrb_value x)
   return mrb_int_value(mrb, hash);
 }
 
+/* to be used only from mruby-sprintf */
 mrb_value
-mrb_bint_2comp(mrb_state *mrb, mrb_value x, mrb_int base)
+mrb_bint_2comp(mrb_state *mrb, mrb_value x)
 {
   struct RBigint *b = RBIGINT(x);
-  mrb_int i;
 
-  for (i=b->mp.sz-1; i>=0; i--) {
-    if (b->mp.p[i] > 0) break;
-  }
-
-#ifdef __GNUC__
-  mrb_int dbits = __builtin_ctz(base);
-#else
-  mrb_int dbits;
-  switch (base) {
-  case 16: dbits = 4; break;
-  case  8: dbits = 3; break;
-  case  2: dbits = 1; break;
-  }
-#endif
-  mrb_int topbit = DIG_SIZE * (i+1) - lzb(b->mp.p[i]);
-  mrb_int nbits = (topbit / dbits + 1) * dbits;
-
-  mpz_t one;
-  mpz_t up;
   struct RBigint *b2 = bint_new(mrb);
-
-  /* rounding up to nearest power of 2 */
-  mpz_init_set_int(mrb, &one, 1);
-  mpz_init(mrb, &up);
-  mpz_mul_2exp(mrb, &up, &one, nbits);
-  mpz_clear(mrb, &one);
-  mpz_add(mrb, &b2->mp, &up, &b->mp);
-  mpz_clear(mrb, &up);
+  mpz_set(mrb, &b2->mp, &b->mp);
+  mpz_2comp(mrb, &b2->mp);
+  b2->mp.sn = 1;
 
   return mrb_obj_value(b2);
 }
diff --git a/mrbgems/mruby-sprintf/src/sprintf.c b/mrbgems/mruby-sprintf/src/sprintf.c
index 3e511d54e..6ebe8fab9 100644
--- a/mrbgems/mruby-sprintf/src/sprintf.c
+++ b/mrbgems/mruby-sprintf/src/sprintf.c
@@ -17,7 +17,7 @@
 #define BITSPERDIG MRB_INT_BIT
 #define EXTENDSIGN(n, l) (((~0U << (n)) >> (((n)*(l)) % BITSPERDIG)) & ~(~0U << (n)))
 
-mrb_value mrb_bint_2comp(mrb_state *mrb, mrb_value x, mrb_int base);
+mrb_value mrb_bint_2comp(mrb_state *mrb, mrb_value x);
 
 static char*
 remove_sign_bits(char *str, int base)
@@ -599,7 +599,7 @@ retry:
               mrb_int n = (mrb_bint_cmp(mrb, val, mrb_fixnum_value(0)));
               mrb_bool need_dots = ((flags & FPLUS) == 0) && (base == 16 || base == 8 || base == 2) && n < 0;
               if (need_dots) {
-                val = mrb_bint_2comp(mrb, val, base);
+                val = mrb_bint_2comp(mrb, val);
                 dots = 1;
                 v = -1;
               }
@@ -665,6 +665,11 @@ retry:
           fc = '1'; break;
         }
 
+        if (dots) {
+          while (*s == fc) {
+            s++; len--;
+          }
+        }
         if (*p == 'X') {
           char *pp = s;
           int c;
@@ -672,7 +677,7 @@ retry:
             *pp = toupper(c);
             pp++;
           }
-          if (base == 16 && fc) {
+          if (base == 16) {
             fc = 'F';
           }
         }