From 3621a04cf020cba747ba75136aec7a575890cceb Mon Sep 17 00:00:00 2001
From: Thomas Voss <mail@thomasvoss.com>
Date: Mon, 26 Aug 2024 09:04:11 +0200
Subject: Huge overhall; fix code; remove external deps

---
 src/base32.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 src/base32.c

(limited to 'src/base32.c')

diff --git a/src/base32.c b/src/base32.c
new file mode 100644
index 0000000..82c5b48
--- /dev/null
+++ b/src/base32.c
@@ -0,0 +1,93 @@
+#include <assert.h>
+
+#include "base32.h"
+#include "common.h"
+
+static inline bool b32blktoa(uint8_t *restrict, const uint8_t *restrict)
+	__attribute__((always_inline));
+
+static const uint8_t lookup[] = {
+	/* [00…07] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [08…0F] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [10…17] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [18…1F] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [20…27] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [28…2F] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [30…37] = */ 0xFF, 0xFF,   26,   27,   28,   29,   30,   31,
+	/* [38…3F] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,    0, 0xFF, 0xFF,
+	/* [40…47] = */ 0xFF,    0,    1,    2,    3,    4,    5,    6,
+	/* [48…4F] = */    7,    8,    9,   10,   11,   12,   13,   14,
+	/* [50…57] = */   15,   16,   17,   18,   19,   20,   21,   22,
+	/* [58…5F] = */   23,   24,  25,  0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [60…67] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [68…6F] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [70…77] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [78…7F] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [80…87] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [88…8F] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [90…97] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [98…9F] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [A0…A7] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [A8…AF] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [B0…B7] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [B8…BF] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [C0…C7] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [C8…CF] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [D0…D7] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [D8…DF] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [E0…E7] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [E8…EF] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [F0…F7] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+	/* [F8…FF] = */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+};
+
+bool
+b32toa(uint8_t *restrict dst, const char *restrict src, size_t len)
+{
+	assert(len != 0);
+
+	size_t i, j;
+	for (i = j = 0; len - i >= 8; i += 8, j += 5) {
+		uint8_t bits[] = {
+			lookup[(uint8_t)src[i + 0]],
+			lookup[(uint8_t)src[i + 1]],
+			lookup[(uint8_t)src[i + 2]],
+			lookup[(uint8_t)src[i + 3]],
+			lookup[(uint8_t)src[i + 4]],
+			lookup[(uint8_t)src[i + 5]],
+			lookup[(uint8_t)src[i + 6]],
+			lookup[(uint8_t)src[i + 7]],
+		};
+		if (!b32blktoa(dst + j, bits))
+			return false;
+	}
+
+	uint8_t bits[8] = {0};
+	switch (len - i) {
+	case 7: bits[6] = lookup[(uint8_t)src[i + 6]]; /* fallthrough */
+	case 6: bits[5] = lookup[(uint8_t)src[i + 5]]; /* fallthrough */
+	case 5: bits[4] = lookup[(uint8_t)src[i + 4]]; /* fallthrough */
+	case 4: bits[3] = lookup[(uint8_t)src[i + 3]]; /* fallthrough */
+	case 3: bits[2] = lookup[(uint8_t)src[i + 2]]; /* fallthrough */
+	case 2: bits[1] = lookup[(uint8_t)src[i + 1]]; /* fallthrough */
+	case 1: bits[0] = lookup[(uint8_t)src[i + 0]];
+		return b32blktoa(dst + j, bits);
+	}
+	return true;
+}
+
+bool
+b32blktoa(uint8_t *restrict dst, const uint8_t *restrict src)
+{
+	uint8_t or = src[0] | src[1] | src[2] | src[3]
+	           | src[4] | src[5] | src[6] | src[7];
+	if (or == 0xFF)
+		return false;
+
+	dst[0] = src[0]<<3 | src[1]>>2;
+	dst[1] = src[1]<<6 | src[2]<<1 | src[3]>>4;
+	dst[2] = src[3]<<4 | src[4]>>1;
+	dst[3] = src[4]<<7 | src[5]<<2 | src[6]>>3;
+	dst[4] = src[6]<<5 | src[7]>>0;
+	return true;
+}
-- 
cgit v1.2.3