From 413cc53c97f5a665bf84098b47e8d2267002f3ce Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Sat, 18 May 2024 19:32:31 +0200
Subject: Added esep inverse coord

---
 src/cube_portable.h | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

(limited to 'src/cube_portable.h')

diff --git a/src/cube_portable.h b/src/cube_portable.h
index 24c39e8..cb4d8fc 100644
--- a/src/cube_portable.h
+++ b/src/cube_portable.h
@@ -256,6 +256,31 @@ set_eo_fast(cube_fast_t *cube, int64_t eo)
 _static_inline cube_fast_t
 invcoord_fast_esep(int64_t esep)
 {
-	/* TODO */
-	return cubetofast(zero);
+	cube_fast_t ret;
+	int64_t i, j, k, l, s, v, w, is1, set1, set2;
+	uint8_t bit2, bit1;
+	uint8_t slice[3] = {0};
+
+	ret = cubetofast(solved);
+	set1 = esep % 70;
+	set2 = esep / 70;
+
+	for (i = 0, j = 0, k = 4, l = 4; i < 12; i++) {
+		v = binomial[11-i][k];
+		w = binomial[7-j][l];
+		bit2 = set2 >= v;
+		bit1 = set1 >= w;
+		is1 = (1 - bit2) * bit1;
+
+		set2 -= bit2 * v;
+		k -= bit2;
+		set1 -= is1 * w;
+		l -= is1;
+		j += (1-bit2);
+		s = 2*bit2 + (1-bit2)*bit1;
+
+		ret.edge[i] = (slice[s]++) | (s << 2);
+	}
+
+	return ret;
 }
-- 
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