Added unpack function to exomiser

bitshifters · Jul 6, 2016 · 48f9cae · 48f9cae
1 parent 2631177
commit 48f9cae
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diff --git a/lib/exomiser.h.6502 b/lib/exomiser.h.6502
@@ -8,6 +8,8 @@
 \\ Plus ZP vars
 \\ Exomiser decruncher routine installs empty NMI handler at &0d00
 
+\\ Compress data using:
+\\ exomizer.exe raw -c -m 1024 <file.raw> -o <file.exo>
 
 \ ******************************************************************
 \ *	Space reserved for runtime buffers not preinitialised

diff --git a/lib/exomiser.s.6502 b/lib/exomiser.s.6502
@@ -5,6 +5,26 @@
 
 .exo_start
 
+; -------------------------------------------------------------------
+; Unpack a compressed data stream previously initialized by exo_init_decruncher
+; to the memory address specified in X,Y
+.exo_unpack
+{
+	STX write_chr+1
+	STY write_chr+2
+
+	.next_chr
+	JSR exo_get_decrunched_byte
+	BCS all_done
+	.write_chr	STA &ffff				; **SELF-MODIFIED**
+	INC write_chr+1
+	BNE next_chr
+	INC write_chr+2
+	BNE next_chr
+	.all_done
+	RTS
+}
+
 ; -------------------------------------------------------------------
 ; Fetch byte from an exomiser compressed data stream
 ; for this exo_get_crunched_byte routine to work the crunched data has to be
@@ -37,6 +57,7 @@ EXO_crunch_byte_hi = exo_get_crunched_byte + 10
 ; zero page locations and the decrunch tables
 ; no constraints on register content, however the
 ; decimal flag has to be #0 (it almost always is, otherwise do a cld)
+; X/Y contains address of EXO crunched data stream
 ; -------------------------------------------------------------------
 .exo_init_decruncher				; pass in address of (crunched data-1) in X,Y
 {