base64

include/tlibc/base64.h

@@ -0,0 +1,23 @@
+#pragma once
+#include "tlibc/std.h"
+
+/// @param src_size size of data to encode
+/// @return number of encoded characters. Is a multiple of 4.
+u32 base64_encodedSize(u32 src_size);
+
+/// @param src data to encode
+/// @param src_size size of data to encode
+/// @param dst buffer of size base64_encodedSize(src_size)
+/// @return number of encoded characters. Is a multiple of 4.
+u32 base64_encode(const u8* src, u32 src_size, char* dst);
+
+/// @param src data to decode
+/// @param src_size size of data to decode. Must be a multiple of 4 for valid base64 data.
+/// @return number of decoded characters or 0 on error
+u32 base64_decodedSize(const char* src, u32 src_size);
+
+/// @param src data to decode
+/// @param src_size size of data to decode. Must be a multiple of 4 for valid base64 data.
+/// @param dst buffer of size base64_decodedSize(src, src_size)
+/// @return number of decoded characters or 0 on error
+u32 base64_decode(const u8* src, u32 src_size, u8* dst);

src/base64.c

@@ -0,0 +1,86 @@
+#include "tlibc/base64.h"
+
+// based on https://nachtimwald.com/2017/11/18/base64-encode-and-decode-in-c
+
+u32 base64_encodedSize(u32 src_size){
+	u32 ret = src_size;
+	if (src_size % 3 != 0)
+		ret += 3 - (src_size % 3);
+	ret /= 3;
+	ret *= 4;
+	return ret;
+}
+
+static const char b64chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+u32 base64_encode(const u8* src, u32 src_size, char* dst){
+    u32 i = 0, j = 0, v = 0;
+    for (; i < src_size; i += 3) {
+		v = src[i];
+		v = i + 1 < src_size ? v << 8 | src[i + 1] : v << 8;
+		v = i + 2 < src_size ? v << 8 | src[i + 2] : v << 8;
+
+		dst[j++] = b64chars[(v >> 18) & 0x3F];
+		dst[j++] = b64chars[(v >> 12) & 0x3F];
+        dst[j++] = i + 1 < src_size ? b64chars[(v >> 6) & 0x3F] : '=';
+        dst[j++] = i + 2 < src_size ? b64chars[v & 0x3F] : '=';
+	}
+
+    return j;
+}
+
+u32 base64_decodedSize(const char* src, u32 src_size){
+    // incomplete src
+    if(src_size % 4 != 0)
+        return 0;
+
+    u32 ret = src_size / 4 * 3;
+    u32 i = src_size;
+    while(i > 0 && src[--i] == '=') {
+        ret--;
+    }
+    return ret;
+}
+
+/*
+void base64_generateDecodeTable(){
+	int inv[80];
+	memset(inv, -1, sizeof(inv));
+	for (u32 i = 0; i < 64; i + +) {
+		inv[b64chars[i] - 43] = i;
+	}
+}
+*/
+
+static int b64inverse[] = { 
+    62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58,
+	59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5,
+	6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
+	21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28,
+	29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42,
+	43, 44, 45, 46, 47, 48, 49, 50, 51
+};
+
+u32 base64_decode(const u8* src, u32 src_size, u8* dst){
+    // incomplete src
+    if(src_size % 4 != 0)
+        return 0;
+
+    u32 i = 0, j = 0, v = 0;
+    for (; i < src_size; i += 4) {
+		v = b64inverse[src[i] - 43];
+		v = (v << 6) | b64inverse[src[i + 1] - 43];
+		v = src[i + 2]=='=' ? v << 6 : (v << 6) | b64inverse[src[i + 2] - 43];
+		v = src[i + 3]=='=' ? v << 6 : (v << 6) | b64inverse[src[i + 3] - 43];
+
+		dst[j++] = (v >> 16) & 0xFF;
+		if (src[i + 2] != '='){
+			dst[j++] = (v >> 8) & 0xFF;
+        }
+		if (src[i + 3] != '='){
+			dst[j++] = v & 0xFF;
+        }
+	}
+
+    return j;
+}