Backport from xs.

data.c

@@ -2,6 +2,7 @@
 /* copyright (c) 2022 - 2023 grunfink et al. / MIT license */
 
 #include "xs.h"
+#include "xs_hex.h"
 #include "xs_io.h"
 #include "xs_json.h"
 #include "xs_openssl.h"

mastoapi.c

@@ -4,6 +4,7 @@
 #ifndef NO_MASTODON_API
 
 #include "xs.h"
+#include "xs_hex.h"
 #include "xs_openssl.h"
 #include "xs_json.h"
 #include "xs_io.h"

snac.c

@@ -4,6 +4,7 @@
 #define XS_IMPLEMENTATION
 
 #include "xs.h"
+#include "xs_hex.h"
 #include "xs_io.h"
 #include "xs_unicode.h"
 #include "xs_json.h"

xs.h

@@ -119,10 +119,6 @@ void xs_data_get(void *data, const xs_data *value);
 
 void *xs_memmem(const char *haystack, int h_size, const char *needle, int n_size);
 
-xs_str *xs_hex_enc(const xs_val *data, int size);
-xs_val *xs_hex_dec(const xs_str *hex, int *size);
-int xs_is_hex(const char *str);
-
 unsigned int xs_hash_func(const char *data, int size);
 
 #ifdef XS_ASSERT
@@ -1178,75 +1174,6 @@ void *xs_memmem(const char *haystack, int h_size, const char *needle, int n_size
 }
 
 
-/** hex **/
-
-static char xs_hex_digits[] = "0123456789abcdef";
-
-xs_str *xs_hex_enc(const xs_val *data, int size)
-/* returns an hexdump of data */
-{
-    xs_str *s;
-    char *p;
-    int n;
-
-    p = s = xs_realloc(NULL, _xs_blk_size(size * 2 + 1));
-
-    for (n = 0; n < size; n++) {
-        *p++ = xs_hex_digits[*data >> 4 & 0xf];
-        *p++ = xs_hex_digits[*data      & 0xf];
-        data++;
-    }
-
-    *p = '\0';
-
-    return s;
-}
-
-
-xs_val *xs_hex_dec(const xs_str *hex, int *size)
-/* decodes an hexdump into data */
-{
-    int sz = strlen(hex);
-    xs_val *s = NULL;
-    char *p;
-    int n;
-
-    if (sz % 2)
-        return NULL;
-
-    p = s = xs_realloc(NULL, _xs_blk_size(sz / 2 + 1));
-
-    for (n = 0; n < sz; n += 2) {
-        int i;
-        if (sscanf(&hex[n], "%02x", &i) == 0) {
-            /* decoding error */
-            return xs_free(s);
-        }
-        else
-            *p = i;
-
-        p++;
-    }
-
-    *p = '\0';
-    *size = sz / 2;
-
-    return s;
-}
-
-
-int xs_is_hex(const char *str)
-/* returns 1 if str is an hex string */
-{
-    while (*str) {
-        if (strchr("0123456789abcdefABCDEF", *str++) == NULL)
-            return 0;
-    }
-
-    return 1;
-}
-
-
 unsigned int xs_hash_func(const char *data, int size)
 /* a general purpose hashing function */
 {

xs_hex.h

@@ -0,0 +1,85 @@
+/* copyright (c) 2022 - 2023 grunfink et al. / MIT license */
+
+#ifndef _XS_HEX_H
+
+#define _XS_HEX_H
+
+xs_str *xs_hex_enc(const xs_val *data, int size);
+xs_val *xs_hex_dec(const xs_str *hex, int *size);
+int xs_is_hex(const char *str);
+
+#ifdef XS_IMPLEMENTATION
+
+/** hex **/
+
+static char rev_hex_digits[] = "fedcba9876543210FEDCBA";
+
+xs_str *xs_hex_enc(const xs_val *data, int size)
+/* returns an hexdump of data */
+{
+    xs_str *s;
+    char *p;
+    int n;
+
+    p = s = xs_realloc(NULL, _xs_blk_size(size * 2 + 1));
+
+    for (n = 0; n < size; n++) {
+        *p++ = rev_hex_digits[0xf - (*data >> 4 & 0xf)];
+        *p++ = rev_hex_digits[0xf - (*data      & 0xf)];
+        data++;
+    }
+
+    *p = '\0';
+
+    return s;
+}
+
+
+xs_val *xs_hex_dec(const xs_str *hex, int *size)
+/* decodes an hexdump into data */
+{
+    int sz = strlen(hex);
+    xs_val *s = NULL;
+    char *p;
+    int n;
+
+    if (sz % 2)
+        return NULL;
+
+    p = s = xs_realloc(NULL, _xs_blk_size(sz / 2 + 1));
+
+    for (n = 0; n < sz; n += 2) {
+        char *d1 = strchr(rev_hex_digits, *hex++);
+        char *d2 = strchr(rev_hex_digits, *hex++);
+
+        if (!d1 || !d2) {
+            /* decoding error */
+            return xs_free(s);
+        }
+
+        *p++ = (0xf - ((d1 - rev_hex_digits) & 0xf)) << 4 |
+               (0xf - ((d2 - rev_hex_digits) & 0xf));
+    }
+
+    *p = '\0';
+    *size = sz / 2;
+
+    return s;
+}
+
+
+int xs_is_hex(const char *str)
+/* returns 1 if str is an hex string */
+{
+    while (*str) {
+        if (strchr(rev_hex_digits, *str++) == NULL)
+            return 0;
+    }
+
+    return 1;
+}
+
+
+#endif /* XS_IMPLEMENTATION */
+
+#endif /* _XS_HEX_H */

xs_version.h

@@ -1 +1 @@
-/* 0932615dfe85e5d8544c4b2052eb66f3a430eb8c */
+/* 416f5ffa99ecd4a3ec25d273b986d3d99dc92d22 */