Brush up some more code

libc/fmt/unbing.c

@@ -220,7 +220,7 @@ int unbing(int c) {
   l = 0;
   r = ARRAYLEN(kCp437i) - 1;
   while (l <= r) {
-    m = (l + r) >> 1;
+    m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
     if ((kCp437i[m] >> 8) < c) {
       l = m + 1;
     } else if ((kCp437i[m] >> 8) > c) {

libc/intrin/asan.c

@@ -743,7 +743,7 @@ static void __asan_report_memory_origin_image(intptr_t a, int z) {
       r = n = st->count;
       k = a - st->addr_base;
       while (l < r) {
-        m = (l + r) >> 1;
+        m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
         if (st->symbols[m].y < k) {
           l = m + 1;
         } else {

libc/intrin/findmemoryinterval.c

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
-#include "libc/intrin/midpoint.h"
 #include "libc/runtime/memtrack.internal.h"
 
 noasan unsigned FindMemoryInterval(const struct MemoryIntervals *mm, int x) {
@@ -25,7 +24,7 @@ noasan unsigned FindMemoryInterval(const struct MemoryIntervals *mm, int x) {
   l = 0;
   r = mm->i;
   while (l < r) {
-    m = _midpoint(l, r);
+    m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
     if (mm->p[m].y < x) {
       l = m + 1;
     } else {

libc/intrin/kprintf.greg.c

@@ -161,7 +161,7 @@ privileged static bool kismapped(int x) {
   if (kismemtrackhosed()) return false;
   r = _weaken(_mmi)->i;
   while (l < r) {
-    m = (l + r) >> 1;
+    m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
     if (_weaken(_mmi)->p[m].y < x) {
       l = m + 1;
     } else {

libc/intrin/midpoint.h

@@ -1,32 +0,0 @@
-#ifndef COSMOPOLITAN_LIBC_BITS_MIDPOINT_H_
-#define COSMOPOLITAN_LIBC_BITS_MIDPOINT_H_
-#include "libc/assert.h"
-#if !(__ASSEMBLER__ + __LINKER__ + 0)
-
-#if defined(__GNUC__) && !defined(__STRICT_ANSI__) && defined(__x86__)
-/**
- * Computes `(a + b) / 2` assuming unsigned.
- *
- * This implementation is the fastest on AMD Zen architecture.
- */
-#define _midpoint(a, b)         \
-  ({                            \
-    typeof((a) + (b)) a_ = (a); \
-    typeof(a_) b_ = (b);        \
-    _unassert(a_ >= 0);         \
-    _unassert(b_ >= 0);         \
-    asm("add\t%1,%0\n\t"        \
-        "rcr\t%0"               \
-        : "+r"(a_)              \
-        : "r"(b_));             \
-    a_;                         \
-  })
-#else
-/**
- * Computes `(a + b) / 2` assuming unsigned.
- */
-#define _midpoint(a, b) (((a) & (b)) + ((a) ^ (b)) / 2)
-#endif /* __GNUC__ && !__STRICT_ANSI__ && x86 */
-
-#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
-#endif /* COSMOPOLITAN_LIBC_BITS_MIDPOINT_H_ */

libc/mem/sortedints.c

@@ -18,7 +18,6 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
 #include "libc/dce.h"
-#include "libc/intrin/midpoint.h"
 #include "libc/mem/mem.h"
 #include "libc/mem/sortedints.internal.h"
 #include "libc/str/str.h"
@@ -28,7 +27,7 @@ bool ContainsInt(const struct SortedInts *t, int k) {
   l = 0;
   r = t->n - 1;
   while (l <= r) {
-    m = _midpoint(l, r);
+    m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
     if (t->p[m] < k) {
       l = m + 1;
     } else if (t->p[m] > k) {
@@ -45,7 +44,7 @@ int LeftmostInt(const struct SortedInts *t, int k) {
   l = 0;
   r = t->n;
   while (l < r) {
-    m = _midpoint(l, r);
+    m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
     if (t->p[m] < k) {
       l = m + 1;
     } else {

libc/runtime/getsymbol.c

@@ -41,7 +41,7 @@ dontinstrument privileged int __get_symbol(struct SymbolTable *t, intptr_t a) {
     r = n = t->count;
     k = a - t->addr_base;
     while (l < r) {
-      m = (l + r) >> 1;
+      m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
       if (t->symbols[m].y < k) {
         l = m + 1;
       } else {

libc/sock/closesocket-nt.c

@@ -30,7 +30,8 @@ textwindows int sys_closesocket_nt(struct Fd *fd) {
   struct SockFd *sockfd;
   sockfd = (struct SockFd *)fd->extra;
   free(sockfd);
-  if (__sys_closesocket_nt(fd->handle) != -1) {
+  int rc = __sys_closesocket_nt(fd->handle);
+  if (rc != -1) {
     return 0;
   } else {
     return __winsockerr();

libc/str/crc32c.c

@@ -39,7 +39,7 @@ uint32_t crc32c(uint32_t init, const void *data, size_t size) {
   static uint32_t kCrc32cTab[256];
   if (!once) {
     crc32init(kCrc32cTab, 0x82f63b78);
-    once = 0;
+    once = 1;
   }
   p = data;
   pe = p + size;

libc/str/iswseparator.c

@@ -399,7 +399,7 @@ int iswseparator(wint_t c) {
     l = 0;
     r = n = sizeof(kCodes) / sizeof(kCodes[0]);
     while (l < r) {
-      m = (l + r) >> 1;
+      m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
       if (kCodes[m][1] < c) {
         l = m + 1;
       } else {
@@ -411,7 +411,7 @@ int iswseparator(wint_t c) {
     l = 0;
     r = n = sizeof(kAstralCodes) / sizeof(kAstralCodes[0]);
     while (l < r) {
-      m = (l + r) >> 1;
+      m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
       if (kAstralCodes[m][1] < c) {
         l = m + 1;
       } else {

libc/str/strncpy.c

@@ -24,39 +24,6 @@
  * 1. If SRC is too long, it's truncated and *not* NUL-terminated.
  * 2. If SRC is too short, the remainder is zero-filled.
  *
- * Please note this function isn't designed to prevent untrustworthy
- * data from modifying memory without authorization; the memccpy()
- * function can be used for that purpose.
- *
- * Here's an example of the only use case we know of for strncpy:
- *
- *     static const struct People {
- *       char name[8];
- *       int age;
- *     } kPeople[] = {
- *         {"alice", 29},  //
- *         {"bob", 42},    //
- *     };
- *
- *     int GetAge(const char *name) {
- *       char k[8];
- *       int m, l, r;
- *       l = 0;
- *       r = ARRAYLEN(kPeople) - 1;
- *       strncpy(k, name, 8);
- *       while (l <= r) {
- *         m = (l + r) >> 1;
- *         if (READ64BE(kPeople[m].name) < READ64BE(k)) {
- *           l = m + 1;
- *         } else if (READ64BE(kPeople[m].name) > READ64BE(k)) {
- *           r = m - 1;
- *         } else {
- *           return kPeople[m].age;
- *         }
- *       }
- *       return -1;
- *     }
- *
  * @return dest
  * @see stpncpy(), memccpy()
  * @asyncsignalsafe

libc/str/towlower.c

@@ -201,7 +201,7 @@ wint_t towlower(wint_t c) {
       l = 0;
       r = n = sizeof(kLower) / sizeof(kLower[0]);
       while (l < r) {
-        m = (l + r) >> 1;
+        m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
         if (kLower[m].y < c) {
           l = m + 1;
         } else {
@@ -218,7 +218,7 @@ wint_t towlower(wint_t c) {
     l = 0;
     r = n = sizeof(kAstralLower) / sizeof(kAstralLower[0]);
     while (l < r) {
-      m = (l + r) >> 1;
+      m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
       if (kAstralLower[m][1] < c) {
         l = m + 1;
       } else {

libc/str/towupper.c

@@ -164,7 +164,7 @@ wint_t towupper(wint_t c) {
       l = 0;
       r = n = sizeof(kUpper) / sizeof(kUpper[0]);
       while (l < r) {
-        m = (l + r) >> 1;
+        m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
         if (kUpper[m].y < c) {
           l = m + 1;
         } else {
@@ -181,7 +181,7 @@ wint_t towupper(wint_t c) {
     l = 0;
     r = n = sizeof(kAstralUpper) / sizeof(kAstralUpper[0]);
     while (l < r) {
-      m = (l + r) >> 1;
+      m = (l & r) + ((l ^ r) >> 1);  // floor((a+b)/2)
       if (kAstralUpper[m][1] < c) {
         l = m + 1;
       } else {