1 files changed, 180 insertions, 0 deletions

diff --git a/xs_encdec.h b/xs_encdec.h
new file mode 100644
index 0000000..e336218
--- /dev/null
+++ b/xs_encdec.h
@@ -0,0 +1,180 @@
+/* copyright (c) 2022 grunfink - MIT license */
+
+#ifndef _XS_ENCDEC_H
+
+#define _XS_ENCDEC_H
+
+d_char *xs_hex_enc(const char *data, int size);
+d_char *xs_hex_dec(const char *hex);
+d_char *xs_base64_enc(const char *data, int sz);
+d_char *xs_base64_dec(const char *data, int *size);
+d_char *xs_utf8_enc(d_char *str, unsigned int cpoint);
+
+
+#ifdef XS_IMPLEMENTATION
+
+d_char *xs_hex_enc(const char *data, int size)
+/* returns an hexdump of data */
+{
+    d_char *s;
+    char *p;
+    int n;
+
+    p = s = calloc(size * 2 + 1, 1);
+
+    for (n = 0; n < size; n++) {
+        sprintf(p, "%02x", (unsigned char)data[n]);
+        p += 2;
+    }
+
+    return s;
+}
+
+
+d_char *xs_hex_dec(const char *hex)
+/* decodes an hexdump into data */
+{
+    int sz = strlen(hex);
+    d_char *s;
+    char *p;
+    int n;
+
+    p = s = calloc(sz / 2, 1);
+
+    for (n = 0; n < sz; n += 2) {
+        int i;
+        if (sscanf(&hex[n], "%02x", &i) == 0) {
+            /* decoding error */
+            free(s);
+            s = NULL;
+        }
+        else
+            *p = i;
+
+        p++;
+    }
+
+    return s;
+}
+
+
+d_char *xs_base64_enc(const char *data, int sz)
+/* encodes data to base64 */
+{
+    d_char *s;
+    unsigned char *p;
+    int n;
+    static char *b64_tbl = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+                           "abcdefghijklmnopqrstuvwxyz"
+                           "0123456789+/";
+
+    s = xs_str_new(NULL);
+    p = (unsigned char *)data;
+
+    for (n = 0; n < sz; n += 3) {
+        int l = sz - n;
+
+        if (l == 1) {
+            s = xs_append_m(s, &b64_tbl[(p[n] >> 2) & 0x3f], 1);
+            s = xs_append_m(s, &b64_tbl[(p[n] << 4) & 0x3f], 1);
+            s = xs_append_m(s, "==", 2);
+        }
+        else
+        if (l == 2) {
+            s = xs_append_m(s, &b64_tbl[(p[n] >> 2) & 0x3f], 1);
+            s = xs_append_m(s, &b64_tbl[(p[n] << 4 | p[n + 1] >> 4) & 0x3f], 1);
+            s = xs_append_m(s, &b64_tbl[(p[n + 1] << 2) & 0x3f], 1);
+            s = xs_append_m(s, "=", 1);
+        }
+        else {
+            s = xs_append_m(s, &b64_tbl[(p[n] >> 2) & 0x3f], 1);
+            s = xs_append_m(s, &b64_tbl[(p[n] << 4 | p[n + 1] >> 4) & 0x3f], 1);
+            s = xs_append_m(s, &b64_tbl[(p[n + 1] << 2 | p[n + 2] >> 6) & 0x3f], 1);
+            s = xs_append_m(s, &b64_tbl[(p[n + 2]) & 0x3f], 1);
+        }
+    }
+
+    return s;
+}
+
+
+d_char *xs_base64_dec(const char *data, int *size)
+/* decodes data from base64 */
+{
+    d_char *s = NULL;
+    int sz = 0;
+    char *p;
+    static char *b64_tbl = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+                           "abcdefghijklmnopqrstuvwxyz"
+                           "0123456789+/=";
+
+    p = (char *)data;
+
+    for (p = (char *)data; *p; p += 4) {
+        int cs[4];
+        int n;
+        unsigned char tmp[3];
+
+        for (n = 0; n < 4; n++) {
+            char *ss = strchr(b64_tbl, p[n]);
+
+            if (ss == NULL) {
+                /* not a base64 char */
+                free(s);
+                return NULL;
+            }
+
+            cs[n] = ss - b64_tbl;
+        }
+
+        n = 0;
+
+        /* first byte */
+        tmp[n++] = cs[0] << 2 | ((cs[1] >> 4) & 0x0f);
+
+        /* second byte */
+        if (cs[2] != 64)
+            tmp[n++] = cs[1] << 4 | ((cs[2] >> 2) & 0x3f);
+
+        /* third byte */
+        if (cs[3] != 64)
+            tmp[n++] = cs[2] << 6 | (cs[3] & 0x3f);
+
+        /* must be done manually because data can be pure binary */
+        s = realloc(s, sz + n);
+        memcpy(s + sz, tmp, n);
+        sz += n;
+    }
+
+    *size = sz;
+
+    return s;
+}
+
+
+d_char *xs_utf8_enc(d_char *str, unsigned int cpoint)
+/* encodes an Unicode codepoint to utf8 */
+{
+    unsigned char tmp[4];
+    int n = 0;
+
+    if (cpoint < 0x80)
+        tmp[n++] = cpoint & 0xff;
+    else
+    if (cpoint < 0x800) {
+        tmp[n++] = 0xc0 | (cpoint >> 6);
+        tmp[n++] = 0x80 | (cpoint & 0x3f);
+    }
+    else
+    if (cpoint < 0x10000) {
+        tmp[n++] = 0xe0 | (cpoint >> 12);
+        tmp[n++] = 0x80 | ((cpoint >> 6) & 0x3f);
+        tmp[n++] = 0x80 | (cpoint & 0x3f);
+    }
+
+    return xs_append_m(str, (char *)tmp, n);
+}
+
+#endif /* XS_IMPLEMENTATION */
+
+#endif /* _XS_ENCDEC_H */