Add base64 thing

3 files changed, 51 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 00e3b3e..d9a6211 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 words-misc/match_pool
 words-misc/permutations
 monty/monty
+base64/base64
 *.o
diff --git a/base64/Makefile b/base64/Makefile
new file mode 100644
index 0000000..59d1285
--- /dev/null
+++ b/base64/Makefile
@@ -0,0 +1 @@
+base64:
diff --git a/base64/base64.c b/base64/base64.c
new file mode 100644
index 0000000..e27217c
--- /dev/null
+++ b/base64/base64.c
@@ -0,0 +1,49 @@
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+
+#define BYTES_PER_BLOCK  3
+#define BASE64_PER_BLOCK 4
+
+const char *lookup = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+void dump_base64_block(const unsigned char *data, size_t len, FILE* stream)
+{
+	char out_block[BASE64_PER_BLOCK+1];
+
+	memset(out_block, '=', sizeof(out_block));
+	out_block[4] = '\0';
+
+	switch(len) {
+	case 3:
+		out_block[3] = lookup[data[2] & 0x3F];
+	case 2:
+		out_block[2] = lookup[(data[1] & 0x0F) << 2 | data[2] >> 6];
+	case 1:
+		out_block[1] = lookup[(data[0] & 0x03) << 4 | (data[1] & 0xF0) >> 4];
+		out_block[0] = lookup[data[0] >> 2];
+		fputs(out_block, stream);
+		break;
+	default:
+		break;
+	}
+}
+
+void dump_base64(FILE* in, FILE* out)
+{
+	size_t nread = 0;
+	char buffer[BYTES_PER_BLOCK+1];
+
+	while (!feof(in)) {
+		nread = fread(buffer, 1, BYTES_PER_BLOCK, in);
+		buffer[nread] = '\0';
+		dump_base64_block(buffer, nread, out);
+	}
+}
+
+int main(void)
+{
+	dump_base64(stdin, stdout);
+	fputc('\n', stdout);
+}