Refine non-intuitive bitwise operations

- Replace non-intuitive left shifts with multiplication - Replace non-intuitive right shifts with division with unsigned divisor - include/config.h: macro `TAB_STOP` & util/poststat.c: macro `HASHSIZE`: Lift the restriction that each of these macros must be a power of 2. - Replace non-intuitive bitwise `and`s with modulo with unsigned divisor - maple/xover.c: `xo_thread()`: Lift the restriction that macro `RS_FORWARD` must be `2`. A modern compiler will transform those operations into bitwise operations, and therefore it is a waste of time to do this by the programmers.
ccns · Feb 13, 2020 · ede75ca · ede75ca
1 parent 22d3fe4
commit ede75ca
Show file tree

Hide file tree

Showing 43 changed files with 173 additions and 175 deletions.
diff --git a/include/config.h b/include/config.h
@@ -512,7 +512,7 @@
 
 #define MOVIE_LINES     (11)            /* 動畫最多有 11 列 */
 
-#define MENU_XPOS       ((d_cols >> 1) + 23)  /* 選單開始的 (y, x) 座標 */
+#define MENU_XPOS       (d_cols / 2U + 23)    /* 選單開始的 (y, x) 座標 */
 #define MENU_YPOS       13
 #define MENU_LOAD       1
 #define MENU_DRAW       2

diff --git a/include/struct.h b/include/struct.h
@@ -36,8 +36,7 @@
 
 #define T_LINES         50             /* maximum total lines */
 #define T_COLS          120            /* maximum total columns，要比 ANSILINELEN 小 */
-#define TAB_STOP        4              /* 按 TAB 換成幾格空白 (要是 2 的次方) */
-#define TAB_WIDTH       (TAB_STOP - 1)
+#define TAB_STOP        4U             /* 按 TAB 換成幾格空白 (建議是 2 的次方，可免去除法) */
 
 #define SCR_WIDTH       80
 /* #define VE_WIDTH        (ANSILINELEN - 1) */

diff --git a/innbbsd/channel.c b/innbbsd/channel.c
@@ -375,7 +375,7 @@ channelreader(
     if (len < ReadSize + 3)
     {
         len += (used + ReadSize);
-        len += (len >> 3);
+        len += (len / 8U);
 
         in->data = data = (char *) realloc(data, len);
         len -= used;

diff --git a/innbbsd/convcode.c b/innbbsd/convcode.c
@@ -34,8 +34,8 @@ conv_init(void)
     if (BtoG != NULL)
         return;
 
-    BGsize = BtoG_count << 1;   /* 每個漢字 2-byte */
-    GBsize = GtoB_count << 1;
+    BGsize = 2 * BtoG_count;    /* 每個漢字 2-byte */
+    GBsize = 2 * GtoB_count;
     BtoG = (unsigned char *) malloc(BGsize + GBsize);
     GtoB = BtoG + BGsize;
 

diff --git a/innbbsd/history.c b/innbbsd/history.c
@@ -90,7 +90,7 @@ void
     str_ncpy(his.xname, xname, sizeof(his.xname));
 
     /* 依 msgid 將 history 打散至 32 個檔案 */
-    sprintf(fpath, "innd/history/%02d", his.hash & 31);
+    sprintf(fpath, "innd/history/%02d", his.hash % 32U);
     rec_add(fpath, &his, sizeof(HIS));
 }
 
@@ -110,7 +110,7 @@ void
 
     /* 依 msgid 找出在哪一份 history 檔案中 */
     hash = str_hash(msgid, 1);
-    sprintf(fpath, "innd/history/%02d", hash & 31);
+    sprintf(fpath, "innd/history/%02d", hash % 32U);
 
     /* 去該份 history 檔案中找看看有沒有 */
     if ((fd = open(fpath, O_RDONLY)) >= 0)

diff --git a/lib/archiv32.c b/lib/archiv32.c
@@ -10,10 +10,10 @@ void archiv32(time_t chrono,    /* 32 bits */
     *str = '\0';
     for (;;)
     {
-        *(--str) = radix32[chrono & 31];
+        *(--str) = radix32[chrono % 32U];
         if (str == fname)
             return;
-        chrono >>= 5;
+        chrono /= 32U;
     }
 }
 
@@ -27,9 +27,9 @@ void archiv32m(time_t chrono,    /* 32 bits */
     *str = '\0';
     for (;;)
     {
-        *(--str) = radix32[chrono & 31];
+        *(--str) = radix32[chrono % 32U];
         if (str == fname)
             return;
-        chrono >>= 5;
+        chrono /= 32U;
     }
 }
diff --git a/lib/chrono32.c b/lib/chrono32.c
@@ -12,7 +12,7 @@ GCC_PURE time_t chrono32(const char *str  /* M0123456 */
         ch -= '0';
         if (ch >= 10)
             ch -= 'A' - '0' - 10;
-        chrono = (chrono << 5) + ch;
+        chrono = (32 * chrono) + ch;
     }
     return chrono;
 }
diff --git a/lib/date_str.c b/lib/date_str.c
@@ -47,7 +47,7 @@ char *Ctime(const time_t * clock)
 
     sprintf(datemsg, "%d年%2d月%2d日%3d:%02d:%02d 星期%.2s",
             t->tm_year - 11, t->tm_mon + 1, t->tm_mday,
-            t->tm_hour, t->tm_min, t->tm_sec, &week[t->tm_wday << 1]);
+            t->tm_hour, t->tm_min, t->tm_sec, &week[2 * t->tm_wday]);
     return (datemsg);
 }
 

diff --git a/lib/header.c b/lib/header.c
@@ -22,7 +22,7 @@ void hdr_fpath(char *fpath, const char *folder, const HDR * hdr)
     folder = hdr->xname;
     cc = *folder;
     if (cc != '@')
-        cc = radix32[chrono & 31];
+        cc = radix32[chrono % 32U];
 
     if (*str == '.')
     {
@@ -98,7 +98,7 @@ int hdr_stamp(const char *folder, int token, HDR * hdr, char *fpath)
 
     for (;;)
     {
-        *family = radix32[chrono & 31];
+        *family = radix32[chrono % 32U];
         archiv32(chrono, fname);
 
         if (flink)

diff --git a/lib/string.c b/lib/string.c
@@ -632,7 +632,7 @@ GCC_PURE int str_hash2(const char *str, int seed)
 
     while ((cc = *str++))
     {
-        seed = (seed << 7) - seed + cc;    /* 127 * seed + cc */
+        seed = 127 * seed + cc;
     }
     return (seed & 0x7fffffff);
 }
@@ -643,7 +643,7 @@ GCC_PURE int str_hash(const char *str, int seed)
 
     while ((cc = *str++))
     {
-        seed = (seed << 5) - seed + cc;    /* 31 * seed + cc */
+        seed = 31 * seed + cc;
     }
     return (seed & 0x7fffffff);
 }
@@ -1326,7 +1326,7 @@ GCC_PURE int hash32(const char *str)
     xo = 1048583;               /* a big prime number */
     while ((cc = *str++))
     {
-        xo = (xo << 5) - xo + cc;    /* 31 * xo + cc */
+        xo = 31 * xo + cc;
     }
     return (xo & 0x7fffffff);
 }
diff --git a/lib/xsort.c b/lib/xsort.c
@@ -77,7 +77,7 @@ void xsort(void *a, size_t n, size_t es, int (*cmp) (const void *lhs, const void
         pn = (char *)a + (n - 1) * es;
         if (n > 40)
         {
-            d = (n >> 3) * es;
+            d = (n / 8U) * es;
             pl = med3(pl, pl + d, pl + d + d, cmp);
             pm = med3(pm - d, pm, pm + d, cmp);
             pn = med3(pn - 2 * d, pn - d, pn, cmp);

diff --git a/maple/acct.c b/maple/acct.c
@@ -236,19 +236,19 @@ void x_file(int mode,            /* M_XFILES / M_UFILES */
         else
         {
             if (n < 21)            /* statue.000703: 註解: 一個畫面只能 show 20 個資料 */
-                move_ansi(n + ((b_lines-21) >> 1), 2);
+                move_ansi(n + (b_lines-21)/2U, 2);
             else
-                move_ansi(n + ((b_lines-21) >> 1) - 20, 2 + ((b_cols+1) >> 1));
+                move_ansi(n + (b_lines-21)/2U - 20, 2 + (b_cols+1)/2U);
 
             prints("(\x1b[1;36m%2d\x1b[m) %s", n, desc);
 
 
             if (mode == M_XFILES)
             {
                 if (n < 21)
-                    move_ansi(n + ((b_lines-21) >> 1), 24 + (d_cols >> 2));    /* Thor.980806: 註解: 印出檔名 */
+                    move_ansi(n + (b_lines-21)/2U, 24 + d_cols/4U);    /* Thor.980806: 註解: 印出檔名 */
                 else
-                    move_ansi(n + ((b_lines-21) >> 1) - 20, 24 + (d_cols >> 2) + ((b_cols+1) >> 1));
+                    move_ansi(n + (b_lines-21)/2U - 20, 24 + d_cols/4U + (b_cols+1)/2U);
                 outs(flist[n - 1] + 4);    /* statue.000703: 註解: +4 去掉目錄 */
                 clrtoeol();
             }
@@ -363,7 +363,7 @@ void bitmsg(const char *msg, const char *str, int level)
             else
                 pbits ^= j;
         }
-        move(5 + (i & 15), (i < 16 ? 0 : 40));
+        move(5 + (i % 16U), (i < 16 ? 0 : 40));
         if (perms[i])
             prints("%c %s %s", radix32[i], msg, perms[i]);
         else
@@ -394,7 +394,7 @@ void bitmsg(const char *msg, const char *str, int level)
             }
 
             pbits ^= j;
-            move(5 + (i & 15), (i < 16 ? 2 : 42));
+            move(5 + (i % 16U), (i < 16 ? 2 : 42));
             outs(msg);
         }
     }

diff --git a/maple/bbsd.c b/maple/bbsd.c
@@ -870,7 +870,7 @@ tn_login(void)
                 level &= ~PERM_CHAT;
 
 /*
-            if ((cuser.numemail >> 4) > (cuser.numlogins + cuser.numposts))
+            if ((cuser.numemail / 16U) > (cuser.numlogins + cuser.numposts))
                 level |= PERM_DENYMAIL;*/
         }
 

diff --git a/maple/board.c b/maple/board.c
@@ -41,7 +41,7 @@ brh_alloc(
     if (size > brh_size)
     {
         /* size = (size & -BRH_PAGE) + BRH_PAGE; */
-        size += n >> 4;         /* 多預約一些記憶體 */
+        size += n / 16U;        /* 多預約一些記憶體 */
         base = (int *) realloc((char *) base, size);
 
         if (base == NULL)

diff --git a/maple/cache.c b/maple/cache.c
@@ -570,7 +570,7 @@ observeshm_find(
     {
         for (count = oshm->total; count > 0;)
         {
-            datum = cache[mid = count >> 1];
+            datum = cache[mid = count / 2U];
             if (userno == datum)
                 return 1;
             if (userno > datum)
@@ -769,7 +769,7 @@ out_rle(
     else
         getyx(&y, &SINKVAL(int));
 
-    move(y, d_cols >> 1/*item_length[count++]*/);
+    move(y, d_cols / 2U /*item_length[count++]*/);
     while ((cc = (unsigned char) *str))
     {
         str++;
@@ -788,7 +788,7 @@ out_rle(
                         outs("\x1b[m");
                         clrtoeol();
                     }
-                    move(++y, d_cols >> 1/*item_length[count++]*/);
+                    move(++y, d_cols / 2U /*item_length[count++]*/);
                 }
                 else
                     outc(cc);
@@ -819,7 +819,7 @@ out_rle(
                 outs("\x1b[m");
                 clrtoeol();
             }
-            move(++y, d_cols >> 1/*item_length[count++]*/);
+            move(++y, d_cols / 2U /*item_length[count++]*/);
 
         }
         else
@@ -861,7 +861,7 @@ film_out(
 
     if (is_movie)               /* random select */
     {
-        tag += (time(0) & 7);   /* 7 steps forward */
+        tag += (time(0) % 8U);  /* 7 steps forward */
         if (tag >= fmax)
             tag = FILM_MOVIE;
     }    /* Thor.980804: 可能是故意的吧? 第一張 random select前八個其中一個 */

diff --git a/maple/edit.c b/maple/edit.c
@@ -596,7 +596,7 @@ ve_string(
             do
             {
                 ve_char(' ');
-            } while (ve_col & TAB_WIDTH);
+            } while (ve_col % TAB_STOP);
         }
         else if (ch == '\n')
         {
@@ -692,7 +692,7 @@ ve_line(
                 {
                     *data++ = ' ';
                     len++;
-                } while ((len & TAB_WIDTH) && (len < VE_WIDTH));
+                } while ((len % TAB_STOP) && (len < VE_WIDTH));
             }
             else if (cc > 2 && cc < ' ' && cc != 27)
             {
@@ -1190,7 +1190,7 @@ quote_check(void)
         checkqt--;
 #endif
 
-    if ((quot_line >> 2) <= post_line)
+    if ((quot_line / 4U) <= post_line)
         return 0;
 
 /*  if (HAS_PERM(PERM_SYSOP))*/
@@ -1427,11 +1427,11 @@ ve_filer(
 //  else
 //  {
         if (bbsmode != M_POST)
-            re = popupmenu_ans2(menu1, "存檔選項", (b_lines >> 1) - 7, (d_cols >> 1) + 20);
+            re = popupmenu_ans2(menu1, "存檔選項", b_lines/2U - 7, d_cols/2U + 20);
         else if (curredit & EDIT_OUTGO)
-            re = popupmenu_ans2(menu2, "存檔選項", (b_lines >> 1) - 7, (d_cols >> 1) + 20);
+            re = popupmenu_ans2(menu2, "存檔選項", b_lines/2U - 7, d_cols/2U + 20);
         else
-            re = popupmenu_ans2(menu3, "存檔選項", (b_lines >> 1) - 7, (d_cols >> 1) + 20);
+            re = popupmenu_ans2(menu3, "存檔選項", b_lines/2U - 7, d_cols/2U + 20);
 
 //  }
 
@@ -1863,7 +1863,7 @@ vedit(
                 do
                 {
                     ve_char(' ');
-                } while (ve_col & (TAB_STOP - 1));
+                } while (ve_col % TAB_STOP);
                 break;
 
             case KEY_INS:               /* Toggle insert/overwrite */
@@ -2190,7 +2190,7 @@ vedit(
                         NULL
                     };
 
-                    switch (cc = popupmenu_ans2(menu, "控制碼選擇", (b_lines >> 1) - 4, (d_cols >> 1) + 20))
+                    switch (cc = popupmenu_ans2(menu, "控制碼選擇", b_lines/2U - 4, d_cols/2U + 20))
                     {
                     case 'i':
                         ve_char(KEY_ESC);

diff --git a/maple/gem.c b/maple/gem.c
@@ -721,7 +721,7 @@ gbuf_malloc(
     {
         if (GemBufferSiz < num)
         {
-            num += (num >> 1);
+            num += (num / 2U);
             GemBufferSiz = num;
             GemBuffer = gbuf = (HDR *) realloc(gbuf, sizeof(HDR) * num);
         }

diff --git a/maple/mail.c b/maple/mail.c
@@ -1953,7 +1953,7 @@ mbox_attr(
     if (type & MAIL_REPLIED)
         return (type & MAIL_MARKED) ? 'R' : 'r';
 
-    return "+ Mm"[type & 3];
+    return "+ Mm"[type % 4U];
 }
 
 

diff --git a/maple/menu.c b/maple/menu.c
@@ -228,9 +228,9 @@ pad_draw(void)
 
     sprintf(str, "\x1b[1;37;46m�W\x1b[34;47m %s \x1b[33m(%s)", cuser.userid, cuser.username);
     len = strlen(str);
-    strcat(str, & " \x1b[30;46m"[len & 1]);
+    strcat(str, & " \x1b[30;46m"[len % 2U]);
 
-    for (i = len >> 1; i < 41; i++)
+    for (i = len / 2U; i < 41; i++)
         strcat(str, "�e");
     sprintf(str2, "\x1b[34;47m %.14s \x1b[37;46m�W\x1b[m\n%-70.70s\n%-70.70s\n%-70.70s\n",
         Etime(&(pad.tpad)), buf[0], buf[1], buf[2]);
@@ -351,7 +351,7 @@ vs_mid(
     }
 
     spc = b_cols - len; /* spc: �����ٳѤU�h�����Ŷ� */
-    pad = spc >> 1; /* pad: Spaces needed to center `mid` */
+    pad = spc / 2U; /* pad: Spaces needed to center `mid` */
 
     prints("%*s%s%*s\x1b[m\n", pad, "", mid, spc - pad, "");
 }
@@ -395,7 +395,7 @@ vs_head(
     spc = b_cols - 14 - len - strlen(currboard); /* spc: �����ٳѤU�h�����Ŷ� */
     len_ttl = BMIN(len_ttl, spc); /* Truncate `title` if too long */
     spc -= len_ttl; /* �\�� title �H��A�����٦� spc ��Ŷ� */
-    pad = BMAX(((b_cols - len) >> 1) - (len_ttl + 5), 0); /* pad: Spaces needed to center `mid` */
+    pad = BMAX((b_cols - len)/2U - (len_ttl + 5), 0U); /* pad: Spaces needed to center `mid` */
 
 #ifdef  COLOR_HEADER
     prints("\x1b[1;%2d;37m�i%.*s�j%*s \x1b[33m%s\x1b[1;%2d;37m%*s \x1b[37m�ݪO�m%s�n\x1b[m\n",
@@ -469,7 +469,7 @@ movie(void)
         ptime = localtime(&now);
         sprintf(datemsg, "[%d/%d �P��%.2s ",
             ptime->tm_mon + 1, ptime->tm_mday,
-            & "天一二三四五六"[ptime->tm_wday << 1]);
+            & "�Ѥ@�G�T�|����"[2 * ptime->tm_wday]);
 
         uptime = now + 86400 - ptime->tm_hour * 3600 -
             ptime->tm_min * 60 - ptime->tm_sec;