From 15d1191aebb917dbc9c18b901e7e26a799bb1437 Mon Sep 17 00:00:00 2001
From: Ben Harris <bjh21@bjh21.me.uk>
Date: Thu, 20 Nov 2025 21:51:28 +0000
Subject: [PATCH] Emit a format-14 'cmap' subtable for variation sequences

Now I can put <U+0030, U+FE00> in an HTML file and Firefox will pick the
correct glyphs.
---
 bedstead.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/bedstead.c b/bedstead.c
index 32623ca..f6e134e 100644
--- a/bedstead.c
+++ b/bedstead.c
@@ -231,9 +231,9 @@ static struct glyph {
 #define U_HASVS  0x00200000 /* Is there a variation selector? */
 #define U_VSMASK 0x0F000000 /* Bottom 4 bits of VS code point. */
 #define U_VSSHIFT 24
-#define VS(uvs) ((((long)uvs << U_VSSHIFT) & U_VSMASK) | U_HASVS)
+#define VS(uvs) ((((unsigned long)uvs << U_VSSHIFT) & U_VSMASK) | U_HASVS)
 #define GET_UV(u) (u & U_UVMASK)
-#define GET_UVS(u) ((u & U_VSMASK) >> U_VSSHIFT)
+#define GET_UVS(u) ((u & U_VSMASK) >> U_VSSHIFT | 0xfe00)
 #define NU 0xFFFFFFFF /* No Unicode code point. Must be > all valid values. */
 	char const *name;
 	uint_least16_t flags;
@@ -3845,6 +3845,15 @@ main(int argc, char **argv)
 	docmap(0, 4, 12);  /* Unicode 2.0+, full repertoire */
 	docmap(3, 1, 4);   /* Windows Unicode, BMP only */
 	docmap(3, 10, 12); /* Windows Unicode, full repertoire */
+	/* Variation sequences. */
+	printf("<cmap_format_14 platformID='0' platEncID='5'>\n");
+	for (i = 0; i < lenof(glyphs); i++) {
+		unsigned long u = glyphs[i].unicode;
+		if (u != NU && (u & U_HASVS))
+			printf("<map uv='0x%lx' uvs='0x%lx' name='%s'/>\n",
+			       GET_UV(u), GET_UVS(u), glyphs[i].name);
+	}
+	printf("</cmap_format_14>\n");
 	printf("</cmap>\n");
 
 	dogpos(); /* Must be before 'CFF ' because it uses glyph bitmaps. */
-- 
2.30.2