From 677feaa727bccd8fbae4c852caabb87bca2f00a9 Mon Sep 17 00:00:00 2001
From: Adrian Cochrane <adrian@openwork.nz>
Date: Fri, 2 Feb 2024 16:25:54 +1300
Subject: [PATCH] Implement a scanner on C-side (LibCMP doesn't provide it).

---
 cbits/transcode.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/cbits/transcode.c b/cbits/transcode.c
index 4efb28c..310f314 100644
--- a/cbits/transcode.c
+++ b/cbits/transcode.c
@@ -382,3 +382,46 @@ bool encodeFontSet(cmp_ctx_t *bytes, FcFontSet *data) {
     }
     return true;
 }
+
+struct bytes {
+    uint8_t *start;
+    size_t offset;
+    size_t length;
+};
+
+bool bytes_reader(struct cmp_ctx_s *ctx, void *data, size_t limit) {
+    struct bytes *bytes = ctx->buf;
+    if (bytes->offset + limit > bytes->length) return false;
+    data = bytes->start + bytes->offset;
+    bytes->offset += limit;
+    return true;
+}
+
+bool bytes_skipper(struct cmp_ctx_s *ctx, size_t count) {
+    struct bytes *bytes = ctx->buf;
+    if (bytes->offset + count > bytes->length) return false;
+    bytes->offset += count;
+    return true;
+}
+
+size_t bytes_writer(struct cmp_ctx_s *ctx, const void *data, size_t count) {
+    struct bytes *bytes = ctx->buf;
+    if (bytes->offset + count > bytes->length) return 0;
+    memcpy(bytes->start + bytes->offset, data, count);
+    bytes->offset += count;
+    return count;
+}
+
+void cmp_bytes_init(cmp_ctx_t *ctx, uint8_t *buf, size_t length) {
+    struct bytes *inner = malloc(sizeof(struct bytes));
+    inner->start = buf;
+    inner->offset = 0;
+    inner->length = length;
+    cmp_init(ctx, inner, bytes_reader, bytes_skipper, bytes_writer);
+}
+
+void cmp_bytes_free(cmp_ctx_t *ctx) {
+    struct bytes *bytes = ctx->buf;
+    free(bytes->start);
+    free(bytes);
+}
-- 
2.30.2