1 files changed, 93 insertions, 0 deletions
diff --git a/app/tools/halibut/charset/big5enc.c b/app/tools/halibut/charset/big5enc.c
new file mode 100644
index 0000000..d3e48ff
--- /dev/null
+++ b/app/tools/halibut/charset/big5enc.c
@@ -0,0 +1,93 @@
+/*
+ * big5enc.c - multibyte encoding of Big5
+ */
+
+#ifndef ENUM_CHARSETS
+
+#include "charset.h"
+#include "internal.h"
+
+/*
+ * Big5 has no associated data, so `charset' may be ignored.
+ */
+
+static void read_big5(charset_spec const *charset, long int input_chr,
+		      charset_state *state,
+		      void (*emit)(void *ctx, long int output), void *emitctx)
+{
+    UNUSEDARG(charset);
+
+    /*
+     * For reading Big5, state->s0 simply contains the single
+     * stored lead byte when we are half way through a double-byte
+     * character, or 0 if we aren't.
+     */
+
+    if (state->s0 == 0) {
+	if (input_chr >= 0xA1 && input_chr <= 0xFE) {
+	    /*
+	     * Lead byte. Just store it.
+	     */
+	    state->s0 = input_chr;
+	} else {
+	    /*
+	     * Anything else we pass straight through unchanged.
+	     */
+	    emit(emitctx, input_chr);
+	}
+    } else {
+	/*
+	 * We have a stored lead byte. We expect a valid followup
+	 * byte.
+	 */
+	if ((input_chr >= 0x40 && input_chr <= 0x7E) ||
+	    (input_chr >= 0xA1 && input_chr <= 0xFE)) {
+	    emit(emitctx, big5_to_unicode(state->s0 - 0xA1, input_chr - 0x40));
+	} else {
+	    emit(emitctx, ERROR);
+	}
+	state->s0 = 0;
+    }
+}
+
+/*
+ * Big5 is a stateless multi-byte encoding (in the sense that just
+ * after any character has been completed, the state is always the
+ * same); hence when writing it, there is no need to use the
+ * charset_state.
+ */
+
+static int write_big5(charset_spec const *charset, long int input_chr,
+		      charset_state *state,
+		      void (*emit)(void *ctx, long int output), void *emitctx)
+{
+    UNUSEDARG(charset);
+    UNUSEDARG(state);
+
+    if (input_chr == -1)
+	return TRUE;		       /* stateless; no cleanup required */
+
+    if (input_chr < 0x80) {
+	emit(emitctx, input_chr);
+	return TRUE;
+    } else {
+	int r, c;
+	if (unicode_to_big5(input_chr, &r, &c)) {
+	    emit(emitctx, r + 0xA1);
+	    emit(emitctx, c + 0x40);
+	    return TRUE;
+	} else {
+	    return FALSE;
+	}
+    }
+}
+
+const charset_spec charset_CS_BIG5 = {
+    CS_BIG5, read_big5, write_big5, NULL
+};
+
+#else /* ENUM_CHARSETS */
+
+ENUM_CHARSET(CS_BIG5)
+
+#endif /* ENUM_CHARSETS */