From 50f6f0d1235269c3ff4f0534347b8e4663d41aec Mon Sep 17 00:00:00 2001
From: Paul Gardner-Stephen <paul@servalproject.org>
Date: Thu, 25 Apr 2019 16:45:39 +0930
Subject: [PATCH] fix text compression and decompression routines.

---
 c64/basic/print_packed_message.s | 23 +++++++++++++++--------
 src/compress_text.c              | 20 ++++++++++----------
 2 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/c64/basic/print_packed_message.s b/c64/basic/print_packed_message.s
index 2fa33a6b..71e5607f 100644
--- a/c64/basic/print_packed_message.s
+++ b/c64/basic/print_packed_message.s
@@ -100,11 +100,9 @@ found_packed_word:
 	clc
 	adc temp_string_ptr+0
 	sta temp_string_ptr+0
-	sta $0426
 	lda temp_string_ptr+1
 	adc #$00
 	sta temp_string_ptr+1
-	sta $0427
 	ldy #$ff
 
 next_packed_word_char:
@@ -176,21 +174,30 @@ has_nybl:
 no_lo_nybl_char:
 
 	;; If current byte has $0F in low nybl, then the next
-	;; byte is a whole byte shifted left one bit.
-	;; bit 0 indicates if it is the end of the word.
+	;; byte is a whole byte.
 	lda (temp_string_ptr),y
 	and #$0f
-	bne +
+	cmp #$0f
+	beq next_is_literal_char
 
-	;; XXX - Implement decoding of this case
-	
-*
+ready_for_next_char:	
 	cpy #$ff
 	bne next_packed_word_char
 end_of_packed_word:	
 	;; Hit end of packed data
 	rts
 
+next_is_literal_char:	
+	;; Output the literal char, and ready for next char
+	iny
+	tya
+	pha
+	lda (temp_string_ptr),y
+	jsr $ffd2
+	pla
+	tay
+	jmp ready_for_next_char
+	
 is_uncommon_char:
 	;; Lower nybl has offset into low-frequency part of the table
 
diff --git a/src/compress_text.c b/src/compress_text.c
index ae516071..cbde0ada 100644
--- a/src/compress_text.c
+++ b/src/compress_text.c
@@ -293,15 +293,8 @@ int pack_word(const char *w,unsigned char *out,int *len)
 	  fprintf(stderr,"ERROR: Extended characters must be < 0x80\n");
 	  exit(-1);
 	}
-	if (w[j+1]) {
-	  out[(*len)++]=(char_num<<1)+1;
-	  fprintf(stderr," XS[$%02x]",char_num);
-	}
-        else {
-	  out[(*len)++]=(char_num<<1)+0;
-	  fprintf(stderr," XS0[$%02x]\n",char_num);
-	  return 0;
-	}
+	out[(*len)++]=w[j];
+	fprintf(stderr," XS[$%02x]",w[j]);
       } else {
 	if (char_num < (14+13)) {
 	  out[(*len)++]=0xF1+(char_num-14);
@@ -396,9 +389,16 @@ int main(void)
 
   // Now encode the words
   for(int i=0;i<word_count;i++) {
-    pack_word(words[i],packed_words,&packed_len);    
+    fprintf(stderr,"$%03X : ",i);
+    int old_offset=packed_len;
+    pack_word(words[i],packed_words,&packed_len);
+    fprintf(stderr,"    Packing word: ");
+    for(int j=old_offset;j<packed_len;j++)
+      fprintf(stderr," $%02X",packed_words[j]);
+    fprintf(stderr,"\n");
   }
   for(int i=0;keyword_list[i];i++) {
+    fprintf(stderr,"$%03X : ",i);
     pack_word(keyword_list[i],packed_keywords,&packedkey_len);    
   }