From 764e9f839f2b93a7f95b156a09c2c5f2067b95d3 Mon Sep 17 00:00:00 2001
From: Wolfgang Draxinger <Wolfgang.Draxinger@physik.uni-muenchen.de>
Date: Fri, 13 Sep 2013 21:17:08 +0200
Subject: custom base64 decoder

---
 picohttp_base64.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 picohttp_base64.c

(limited to 'picohttp_base64.c')

diff --git a/picohttp_base64.c b/picohttp_base64.c
new file mode 100644
index 0000000..1374bff
--- /dev/null
+++ b/picohttp_base64.c
@@ -0,0 +1,78 @@
+#include "picohttp_base64.h"
+
+void phb64encode(
+	phb64raw_t const raw,
+	size_t count,
+	phb64enc_t enc)
+{
+	switch(count) {
+	default: break;
+	case 2:
+		enc[3] = 0xff; 
+	case 1:
+		enc[2] = 0xff;
+	}
+	switch(count) {
+	default:
+		return;
+	case 4:
+		enc[3] |= ((raw[3] & 0x3f));
+	case 3:
+	case 2:
+		enc[2] |= ((raw[2] & 0xc0) >> 6) | ((raw[1] & 0x0f) << 2);
+	case 1:
+		enc[1] = ((raw[1] & 0xf0) >> 4) | ((raw[0] & 0x03) << 4);
+		enc[0] = ((raw[0] & 0xfc) >> 2);
+	}
+
+	for(int i = 0; i < 4; i++) {
+		if( 26 > enc[i] ) {
+			enc[i] = enc[i] + 'A';
+		} else
+		if( 52 > enc[i] ) {
+			enc[i] = (enc[i]-26) + 'a';
+		} else
+		if( 62 > enc[i] ) {
+			enc[i] = (enc[i]-52) + '0';
+		} else
+		switch( enc[i] ) {
+		case 62: enc[i] = '+'; break;
+		case 63: enc[i] = '/'; break;
+		default: enc[i] = '=';
+		}
+	}
+}
+
+size_t phb64decode(
+	phb64enc_t const enc,
+	phb64raw_t raw)
+{
+	size_t count = 3;
+	phb64enc_t v;
+	for(int i = 0; i < 4; i++) {
+		if( 'A' <= enc[i] && 'Z' >= enc[i] ) {
+			v[i] = enc[i] - 'A';
+		} else
+		if( 'a' <= enc[i] && 'z' >= enc[i] ) {
+			v[i] = enc[i] - 'a' + 26;
+		} else
+		if( '0' <= enc[i] && '9' >= enc[i] ) {
+			v[i] = enc[i] - '0' + 52;
+		} else
+		switch(enc[i]) {
+		case '+': v[i] = 62; break;
+		case '/': v[i] = 63; break;
+		case 0: /* slightly deviating from the RFC, but reasonable */
+		case '=': v[i] = 0;  count--; break;
+		default:
+			  return 0;
+		}
+	}
+
+	raw[0] = ((v[0] & 0x3f) << 2) | ((v[1] & 0x30) >> 4);
+	raw[1] = ((v[1] & 0x0f) << 4) | ((v[2] & 0x3c) >> 2);
+	raw[2] = ((v[2] & 0x03) << 6) | ( v[3] & 0x3f );
+
+	return count;
+}
+
-- 
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