MEDIUM: ist: use local conversion arrays to case conversion

Calling tolower/toupper for each character is slow, a lookup into a
256-byte table is cheaper, especially for common characters used in
header field names which all fit into a cache line. Let's create these
two variables marked weak so that they're included only once.

diff --git a/include/common/ist.h b/include/common/ist.h
index dd0c38903f9ee9f5974c6b589da7a680b792ec5d..04b7e00dc33fd568fb53d1d82b16b5876d92c8c3 100644 (file)
--- a/include/common/ist.h
+++ b/include/common/ist.h
@@ -34,6 +34,78 @@
 
 #include <common/config.h>
 
+/* ASCII to lower case conversion table */
+const unsigned char ist_lc[256] __attribute__((__weak__)) = {
+       0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+       0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+       0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+       0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+       0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+       0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
+       0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+       0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
+       0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
+       0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
+       0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
+       0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
+       0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
+       0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
+       0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
+       0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
+       0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
+       0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
+       0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
+       0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
+       0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
+       0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
+       0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
+       0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
+       0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
+       0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
+       0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
+       0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
+       0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
+       0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
+       0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
+       0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
+};
+
+/* ASCII to upper case conversion table */
+const unsigned char ist_uc[256] __attribute__((__weak__)) = {
+       0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+       0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+       0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+       0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+       0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+       0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
+       0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+       0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
+       0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
+       0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
+       0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,
+       0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
+       0x60, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
+       0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
+       0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,
+       0x58, 0x59, 0x5a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
+       0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
+       0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
+       0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
+       0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
+       0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
+       0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
+       0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
+       0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
+       0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
+       0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
+       0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
+       0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
+       0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
+       0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
+       0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
+       0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
+};
+
 /* This string definition will most often be used to represent a read-only
  * string returned from a function, based on the starting point and its length
  * in bytes. No storage is provided, only a pointer and a length. The types
@@ -255,8 +327,10 @@ static inline int isteqi(const struct ist ist1, const struct ist ist2)
                return 0;
 
        while (l.len--) {
-               if (tolower(*l.ptr) != tolower(*r.ptr))
+               if (*l.ptr != *r.ptr &&
+                   ist_lc[(unsigned char)*l.ptr] != ist_lc[(unsigned char)*r.ptr])
                        return 0;
+
                l.ptr++;
                r.ptr++;
        }
@@ -432,8 +506,7 @@ static inline struct ist ist2bin_lc(char *dst, const struct ist src)
         */
        if (__builtin_expect(ofs < src.len, 1)) {
                do {
-                       char c = src.ptr[ofs];
-                       dst[ofs] = ((unsigned char)(c - 'A') <= 'Z' - 'A') ? c + ('a' - 'A') : c;
+                       dst[ofs] = ist_lc[(unsigned char)src.ptr[ofs]];
                        ofs++;
                } while (__builtin_expect(ofs < src.len, 0));
        }
@@ -455,8 +528,7 @@ static inline struct ist ist2str_lc(char *dst, const struct ist src, size_t coun
         */
        if (__builtin_expect(ofs < src.len, 1)) {
                do {
-                       char c = src.ptr[ofs];
-                       dst[ofs] = ((unsigned char)(c - 'A') <= 'Z' - 'A') ? c + ('a' - 'A') : c;
+                       dst[ofs] = ist_lc[(unsigned char)src.ptr[ofs]];
                        ofs++;
                } while (__builtin_expect(ofs < src.len, 0));
        }
@@ -479,8 +551,7 @@ static inline struct ist ist2bin_uc(char *dst, const struct ist src)
         */
        if (__builtin_expect(ofs < src.len, 1)) {
                do {
-                       char c = src.ptr[ofs];
-                       dst[ofs] = ((unsigned char)(c - 'a') <= 'z' - 'a') ? c + ('A' - 'a') : c;
+                       dst[ofs] = ist_uc[(unsigned char)src.ptr[ofs]];
                        ofs++;
                } while (__builtin_expect(ofs < src.len, 0));
        }
@@ -502,8 +573,7 @@ static inline struct ist ist2str_uc(char *dst, const struct ist src, size_t coun
         */
        if (__builtin_expect(ofs < src.len, 1)) {
                do {
-                       char c = src.ptr[ofs];
-                       dst[ofs] = ((unsigned char)(c - 'a') <= 'z' - 'a') ? c + ('A' - 'a') : c;
+                       dst[ofs] = ist_uc[(unsigned char)src.ptr[ofs]];
                        ofs++;
                } while (__builtin_expect(ofs < src.len, 0));
        }