From 1fa2b732b7b6c1539995fa40605d9bcf807ac357 Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Fri, 12 Dec 2025 04:58:15 -0500
Subject: alf: Cleanup and commentary.

---
 src/crunch.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

(limited to 'src/crunch.c')

diff --git a/src/crunch.c b/src/crunch.c
index f572192..2755248 100644
--- a/src/crunch.c
+++ b/src/crunch.c
@@ -30,6 +30,7 @@ unsigned int input_len, output_len, out_bitpos;
 short tokens[MAX_TOKENS][256];
 
 int token_bits;
+int shiftamt; /* precalculated MAX_BITS - token_bits */
 int max_token;
 int curr_token = INIT_TOKEN;
 int in_pos;
@@ -121,6 +122,9 @@ void init_table(void) {
 	token_bits = INITIAL_BITS;
 	max_token = 1 << INITIAL_BITS;
 	curr_token = INIT_TOKEN;
+
+	/* precalculated for store_token() */
+	shiftamt = MAX_BITS - token_bits;
 }
 
 void check_output_len(void) {
@@ -136,9 +140,9 @@ void inc_output_len(void) {
 	output_buf[output_len] = 0;
 }
 
-#ifdef ALF_ENDIAN_OK
+#if !defined(APPEND_BIT) && defined ALF_ENDIAN_OK
 
-/* This is 20% faster, but it requires knowing the endianness of
+/* This is 25% faster, but it requires knowing the endianness of
    the platform at compile time. See bytorder.h for gory details. */
 union { unsigned int ui; u8 bytes[4]; } ui2bytes;
 
@@ -154,11 +158,17 @@ void store_token(int tok) {
 		putchar('\n');
 	}
 
-	tok <<= (MAX_BITS - token_bits);
-	ui2bytes.ui = tok << (12 - out_bitpos);
+	/* align token so, no matter what its size (9 thru 12),
+	   its top bit is at bit 23 of a 32-bit int. */
+	ui2bytes.ui = tok << ((12 - out_bitpos) + shiftamt);
+
+	/* always append 12 bits (it's quicker to do that than have
+	   conditionals to decide whether the last byte is needed) */
 	output_buf[output_len] |= ui2bytes.bytes[HIBYTE];
 	output_buf[output_len + 1] = ui2bytes.bytes[MIDBYTE];
 	output_buf[output_len + 2] = ui2bytes.bytes[LOBYTE];
+
+	/* update based on actual token size */
 	out_bitpos += token_bits;
 	output_len += out_bitpos / 8;
 	out_bitpos %= 8;
@@ -227,11 +237,12 @@ void make_token(short tok, u8 chr) {
 				dump_tokens();
 			}
 			store_token(TOK_RESET); /* stored at the *old* token size! */
-			token_bits = INITIAL_BITS;
 			init_table();
 			return; /* since we're starting over, *don't* make a token */
 		} else {
 			token_bits++;
+			/* precalculated for store_token() */
+			shiftamt--;
 			if(opt_verbose > 1) {
 				printf("token_bits increased to %d\n", token_bits);
 			}
-- 
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