From 7fd00b85752e07153c7df46a81917f8e97f6e8c9 Mon Sep 17 00:00:00 2001
From: Jose Colon Rodriguez
Date: Tue, 26 Mar 2024 08:15:09 -0400
Subject: Using diff for uppercase mapping

---
 codegen/upper.zig | 14 +++++++-------
 src/CaseData.zig  |  5 +++--
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/codegen/upper.zig b/codegen/upper.zig
index 6fea608..455fe2c 100644
--- a/codegen/upper.zig
+++ b/codegen/upper.zig
@@ -31,26 +31,26 @@ pub fn main() !void {
         if (line.len == 0) continue;
 
         var field_iter = std.mem.splitScalar(u8, line, ';');
-        var cps: [2]u24 = undefined;
+        var cp: i24 = undefined;
 
         var i: usize = 0;
         while (field_iter.next()) |field| : (i += 1) {
             switch (i) {
-                0 => cps[0] = try std.fmt.parseInt(u24, field, 16),
+                0 => cp = try std.fmt.parseInt(i24, field, 16),
+
+                2 => if (line[0] == '<') continue :lines,
 
                 12 => {
                     // Simple uppercase mapping
                     if (field.len == 0) continue :lines;
-                    cps[1] = try std.fmt.parseInt(u24, field, 16);
+                    try writer.writeInt(i24, cp, endian);
+                    const mapping = try std.fmt.parseInt(i24, field, 16);
+                    try writer.writeInt(i24, mapping - cp, endian);
                 },
 
-                2 => if (line[0] == '<') continue :lines,
-
                 else => {},
             }
         }
-
-        for (&cps) |cp| try writer.writeInt(u24, cp, endian);
     }
 
     try writer.writeInt(u24, 0, endian);
diff --git a/src/CaseData.zig b/src/CaseData.zig
index d790e8c..98a74b1 100644
--- a/src/CaseData.zig
+++ b/src/CaseData.zig
@@ -37,9 +37,10 @@ pub fn init(allocator: mem.Allocator) !Self {
     var upper_reader = upper_decomp.reader();
 
     while (true) {
-        const cp = try upper_reader.readInt(u24, endian);
+        const cp = try upper_reader.readInt(i24, endian);
         if (cp == 0) break;
-        self.case_map[cp][0] = @intCast(try upper_reader.readInt(u24, endian));
+        const diff = try upper_reader.readInt(i24, endian);
+        self.case_map[@intCast(cp)][0] = @intCast(cp + diff);
     }
 
     // Lowercase
-- 
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