Fix parsing of hex literals with exponents.
Fix bytecode dump for certain number constants.

--- a/src/lj_lex.c
+++ b/src/lj_lex.c
@@ -137,14 +137,17 @@ static int lex_number64(LexState *ls, TValue *tv)
 /* Parse a number literal. */
 static void lex_number(LexState *ls, TValue *tv)
 {
-  int c;
+  int c, xp = 'E';
   lua_assert(lj_char_isdigit(ls->current));
-  do {
+  if ((c = ls->current) == '0') {
+    save_and_next(ls);
+    if ((ls->current & ~0x20) == 'X') xp = 'P';
+  }
+  while (lj_char_isident(ls->current) || ls->current == '.' ||
+	 ((ls->current == '-' || ls->current == '+') && (c & ~0x20) == xp)) {
     c = ls->current;
     save_and_next(ls);
-  } while (lj_char_isident(ls->current) || ls->current == '.' ||
-	   ((ls->current == '-' || ls->current == '+') &&
-	    ((c & ~0x20) == 'E' || (c & ~0x20) == 'P')));
+  }
 #if LJ_HASFFI
   c &= ~0x20;
   if ((c == 'I' || c == 'L' || c == 'U') && !ctype_ctsG(G(ls->L)))
--- a/src/lj_bcwrite.c
+++ b/src/lj_bcwrite.c
@@ -219,13 +219,19 @@ static void bcwrite_knum(BCWriteCtx *ctx, GCproto *pt)
 	k = lj_num2int(num);
 	if (num == (lua_Number)k) {  /* -0 is never a constant. */
 	save_int:
-	  bcwrite_uleb128(ctx, 2*(uint32_t)k);
-	  if (k < 0) ctx->sb.buf[ctx->sb.n-1] |= 0x10;
+	  bcwrite_uleb128(ctx, 2*(uint32_t)k | ((uint32_t)k & 0x80000000u));
+	  if (k < 0) {
+	    char *p = &ctx->sb.buf[ctx->sb.n-1];
+	    *p = (*p & 7) | ((k>>27) & 0x18);
+	  }
 	  continue;
 	}
       }
-      bcwrite_uleb128(ctx, 1+2*o->u32.lo);
-      if (o->u32.lo >= 0x80000000u) ctx->sb.buf[ctx->sb.n-1] |= 0x10;
+      bcwrite_uleb128(ctx, 1+(2*o->u32.lo | (o->u32.lo & 0x80000000u)));
+      if (o->u32.lo >= 0x80000000u) {
+	char *p = &ctx->sb.buf[ctx->sb.n-1];
+	*p = (*p & 7) | ((o->u32.lo>>27) & 0x18);
+      }
       bcwrite_uleb128(ctx, o->u32.hi);
     }
   }