From a7c404e03a4b814160ec4c97797a56ee4581a0f7 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <m@maandree.se>
Date: Sun, 25 Jan 2026 12:04:20 +0100
Subject: Add yijing n-grams
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Mattias Andrée <m@maandree.se>
---
 libcharconv_latin.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 81 insertions(+), 1 deletion(-)

(limited to 'libcharconv_latin.c')

diff --git a/libcharconv_latin.c b/libcharconv_latin.c
index 9dc81cf..232eb5c 100644
--- a/libcharconv_latin.c
+++ b/libcharconv_latin.c
@@ -2,12 +2,24 @@
 #include "lib-common.h"
 
 
+static unsigned char yijing_hexagrams[] = {
+	0xC0, 0xEB, 0xCC, 0xE0, 0xC9, 0xC5, 0xD8, 0xCB,
+	0xC8, 0xF8, 0xE4, 0xF4, 0xFC, 0xFA, 0xE9, 0xD3,
+	0xCD, 0xF1, 0xDD, 0xF7, 0xE5, 0xFF, 0xD4, 0xE2,
+	0xD9, 0xD1, 0xD5, 0xF3, 0xE8, 0xC3, 0xDA, 0xD6,
+	0xEA, 0xDB, 0xF0, 0xDE, 0xF9, 0xEE, 0xD0, 0xEC,
+	0xC4, 0xEF, 0xFE, 0xE6, 0xFB, 0xDC, 0xC2, 0xC7,
+	0xE1, 0xDF, 0xF6, 0xFD, 0xF5, 0xE7, 0xF2, 0xCF,
+	0xCA, 0xED, 0xE3, 0xCE, 0xD2, 0xC6, 0xD7, 0xC1
+};
+
+
 enum libcharconv_result
 libcharconv_latin(const char *s, size_t slen, size_t *n, uint_least32_t *cp, size_t *ncp)
 {
 	enum libcharconv_result ret = LIBCHARCONV_CONVERTED;
 	uint_least32_t c;
-	char c1, c2, c3, c4, c5;
+	char c1, c2, c3, c4, c5, c6;
 	size_t i, clen;
 	unsigned num;
 
@@ -389,6 +401,39 @@ libcharconv_latin(const char *s, size_t slen, size_t *n, uint_least32_t *cp, siz
 				goto use_switch;
 			goto conv1;
 
+		} else if (UINT32_C(0x2630) <= c && c <= UINT32_C(0x2637)) {
+			/* yijing trigrams */
+			c1 = (c & 1u) ? '2' : '1';
+			c2 = (c & 2u) ? '2' : '1';
+			c3 = (c & 4u) ? '2' : '1';
+			goto conv3;
+
+		} else if (UINT32_C(0x1D306) <= c && c <= UINT32_C(0x1D356)) {
+			/* yijing tetragrams */
+			c -= UINT32_C(0x1D306);
+			c4 = (char)((c % 3u) + (unsigned)'1');
+			c /= 3u;
+			c3 = (char)((c % 3u) + (unsigned)'1');
+			c /= 3u;
+			c2 = (char)((c % 3u) + (unsigned)'1');
+			c /= 3u;
+			c1 = (char)((c % 3u) + (unsigned)'1');
+			goto conv4;
+
+		} else if (UINT32_C(0x4DC0) <= c && c <= UINT32_C(0x4DFF)) {
+			/* yijing hexagrams */
+			c &= 0xFFu;
+			for (i = 0u;; i++)
+				if (yijing_hexagrams[i] == (unsigned char)c)
+					break;
+			c6 = (i &  1u) ? '2' : '1';
+			c5 = (i &  2u) ? '2' : '1';
+			c4 = (i &  4u) ? '2' : '1';
+			c3 = (i &  8u) ? '2' : '1';
+			c2 = (i & 16u) ? '2' : '1';
+			c1 = (i & 32u) ? '2' : '1';
+			goto conv6;
+
 		} else {
 		use_switch:
 			switch (c) {
@@ -542,6 +587,22 @@ libcharconv_latin(const char *s, size_t slen, size_t *n, uint_least32_t *cp, siz
 			case UINT32_C(0xA4FA): c1 = '.'; c2 = '.'; goto conv2;
 			case UINT32_C(0x11FB0): c1 = 'Y'; goto conv1;
 
+			/* yijing monograms */
+			case UINT32_C(0x268A):  c1 = '1'; goto conv1;
+			case UINT32_C(0x268B):  c1 = '2'; goto conv1;
+			case UINT32_C(0x1D300): c1 = '3'; goto conv1;
+
+			/* yijing digrams */
+			case UINT32_C(0x268C):  c1 = '1'; c2 = '1'; goto conv2;
+			case UINT32_C(0x268E):  c1 = '1'; c2 = '2'; goto conv2;
+			case UINT32_C(0x1D301): c1 = '1'; c2 = '3'; goto conv2;
+			case UINT32_C(0x268D):  c1 = '2'; c2 = '1'; goto conv2;
+			case UINT32_C(0x268F):  c1 = '2'; c2 = '2'; goto conv2;
+			case UINT32_C(0x1D302): c1 = '2'; c2 = '3'; goto conv2;
+			case UINT32_C(0x1D303): c1 = '3'; c2 = '1'; goto conv2;
+			case UINT32_C(0x1D304): c1 = '3'; c2 = '2'; goto conv2;
+			case UINT32_C(0x1D305): c1 = '3'; c2 = '3'; goto conv2;
+
 			default:
 			no_match:
 				*n += clen;
@@ -621,4 +682,23 @@ conv5:
 		cp[4] = (uint_least32_t)c5;
 	*ncp = 5u;
 	return ret;
+
+conv6:
+	if (*n)
+		goto no_conv;
+	*n += clen;
+	if (*ncp >= 1u)
+		cp[0] = (uint_least32_t)c1;
+	if (*ncp >= 2u)
+		cp[1] = (uint_least32_t)c2;
+	if (*ncp >= 3u)
+		cp[2] = (uint_least32_t)c3;
+	if (*ncp >= 4u)
+		cp[3] = (uint_least32_t)c4;
+	if (*ncp >= 5u)
+		cp[4] = (uint_least32_t)c5;
+	if (*ncp >= 6u)
+		cp[5] = (uint_least32_t)c6;
+	*ncp = 6u;
+	return ret;
 }
-- 
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