; An optimized LZ4 decompressor
;
- .importzp sp, sreg, regsave, regbank
- .importzp tmp1, tmp2, tmp3, tmp4, ptr1, ptr2, ptr3, ptr4
- .macpack longbranch
- .import memcpy_upwards,pushax,popax
- .export _decompress_lz4
+ .importzp sp, sreg, regsave, regbank
+ .importzp tmp1, tmp2, tmp3, tmp4, ptr1, ptr2, ptr3, ptr4
+ .macpack longbranch
+ .import memcpy_upwards,pushax,popax
+ .export _decompress_lz4
_out = regsave
_written = regsave + 2
; void decompress_lz4 (const u8 *in, u8 * const out, const u16 outlen)
; ---------------------------------------------------------------
-.segment "CODE"
+.segment "CODE"
-.proc _decompress_lz4: near
+.proc _decompress_lz4: near
- sta _outlen
- stx _outlen+1
+ sta _outlen
+ stx _outlen+1
- jsr popax
- sta _out
- stx _out+1
+ jsr popax
+ sta _out
+ stx _out+1
- jsr popax
- sta _in
- stx _in+1
+ jsr popax
+ sta _in
+ stx _in+1
;
; written = 0;
;
- lda #$00
- sta _written
+ lda #$00
+ sta _written
;
; while (written < outlen) {
;
- jmp L0046
+ jmp L0046
;
; token = *in++;
;
-L0004: ldy #0
- lda (_in),y
- sta _token
+L0004: ldy #0
+ lda (_in),y
+ sta _token
- inc _in
- bne L000A
- inc _in+1
+ inc _in
+ bne L000A
+ inc _in+1
L000A:
;
; offset = token >> 4;
;
- ldx #$00
- lsr a
- lsr a
- lsr a
- lsr a
- sta _offset
- stx _offset+1
+ ldx #$00
+ lsr a
+ lsr a
+ lsr a
+ lsr a
+ sta _offset
+ stx _offset+1
;
; token &= 0xf;
; token += 4; // Minmatch
;
- lda _token
- and #$0F
- clc
- adc #4
- sta _token
+ lda _token
+ and #$0F
+ clc
+ adc #4
+ sta _token
;
; if (offset == 15) {
;
- lda _offset
- cmp #$0F
-L0013: bne L001A
+ lda _offset
+ cmp #$0F
+L0013: bne L001A
;
; tmp = *in++;
;
- ldy #0
- lda (_in),y
- sta _tmp
+ ldy #0
+ lda (_in),y
+ sta _tmp
- inc _in
- bne L0017
- inc _in+1
+ inc _in
+ bne L0017
+ inc _in+1
L0017:
;
; offset += tmp;
;
- clc
- adc _offset
- sta _offset
- lda #$00
- adc _offset+1
- sta _offset+1
+ clc
+ adc _offset
+ sta _offset
+ lda #$00
+ adc _offset+1
+ sta _offset+1
;
; if (tmp == 255)
;
- lda _tmp
- cmp #$FF
+ lda _tmp
+ cmp #$FF
;
; goto moreliterals;
;
- jmp L0013
+ jmp L0013
;
; if (offset) {
;
-L001A: lda _offset
- ora _offset+1
- beq L001C
+L001A: lda _offset
+ ora _offset+1
+ beq L001C
;
; memcpy(&out[written], in, offset);
;
- lda _out
- clc
- adc _written
- sta ptr2
- lda _out+1
- adc _written+1
- tax
- lda ptr2
- stx ptr2+1
- jsr pushax
- lda _in
- ldx _in+1
- sta ptr1
- stx ptr1+1
- ldy #0
- jsr memcpy_upwards
+ lda _out
+ clc
+ adc _written
+ sta ptr2
+ lda _out+1
+ adc _written+1
+ tax
+ lda ptr2
+ stx ptr2+1
+ jsr pushax
+ lda _in
+ ldx _in+1
+ sta ptr1
+ stx ptr1+1
+ ldy #0
+ jsr memcpy_upwards
;
; written += offset;
;
- lda _offset
- clc
- adc _written
- sta _written
- lda _offset+1
- adc _written+1
- sta _written+1
+ lda _offset
+ clc
+ adc _written
+ sta _written
+ lda _offset+1
+ adc _written+1
+ sta _written+1
;
; in += offset;
;
- lda _offset
- clc
- adc _in
- sta _in
- lda _offset+1
- adc _in+1
- sta _in+1
+ lda _offset
+ clc
+ adc _in
+ sta _in
+ lda _offset+1
+ adc _in+1
+ sta _in+1
;
; if (written >= outlen)
;
-L001C: lda _written
- cmp _outlen
- lda _written+1
- sbc _outlen+1
+L001C: lda _written
+ cmp _outlen
+ lda _written+1
+ sbc _outlen+1
;
; return;
;
- bcc L0047
- rts
+ bcc L0047
+ rts
;
; memcpy(&offset, in, 2);
;
-L0047: ldy #0
- lda (_in),y
- sta _offset
- iny
- lda (_in),y
- sta _offset+1
+L0047: ldy #0
+ lda (_in),y
+ sta _offset
+ iny
+ lda (_in),y
+ sta _offset+1
;
; in += 2;
;
- lda #$02
- clc
- adc _in
- sta _in
- bcc L002F
- inc _in+1
+ lda #$02
+ clc
+ adc _in
+ sta _in
+ bcc L002F
+ inc _in+1
;
; copysrc = out + written - offset;
;
-L002F: lda _out
- clc
- adc _written
- pha
- lda _out+1
- adc _written+1
- tax
- pla
- sec
- sbc _offset
- sta ptr1
- txa
- sbc _offset+1
- sta ptr1+1
+L002F: lda _out
+ clc
+ adc _written
+ pha
+ lda _out+1
+ adc _written+1
+ tax
+ pla
+ sec
+ sbc _offset
+ sta ptr1
+ txa
+ sbc _offset+1
+ sta ptr1+1
;
; offset = token;
;
- lda #$00
- sta _offset+1
- lda _token
- sta _offset
+ lda #$00
+ sta _offset+1
+ lda _token
+ sta _offset
;
; if (token == 19) {
;
- cmp #$13
-L0045: bne L003C
+ cmp #$13
+L0045: bne L003C
;
; tmp = *in++;
;
- ldy #0
- lda (_in),y
- sta _tmp
+ ldy #0
+ lda (_in),y
+ sta _tmp
- inc _in
- bne L0039
- inc _in+1
+ inc _in
+ bne L0039
+ inc _in+1
L0039:
;
; offset += tmp;
;
- clc
- adc _offset
- sta _offset
- tya
- adc _offset+1
- sta _offset+1
+ clc
+ adc _offset
+ sta _offset
+ tya
+ adc _offset+1
+ sta _offset+1
;
; if (tmp == 255)
;
- lda _tmp
- cmp #$FF
+ lda _tmp
+ cmp #$FF
;
; goto morematches;
;
- jmp L0045
+ jmp L0045
;
; memcpy(&out[written], copysrc, offset);
;
-L003C: lda _out
- clc
- adc _written
- sta ptr2
- lda _out+1
- adc _written+1
- tax
- lda ptr2
- stx ptr2+1
- jsr pushax
- jsr memcpy_upwards
+L003C: lda _out
+ clc
+ adc _written
+ sta ptr2
+ lda _out+1
+ adc _written+1
+ tax
+ lda ptr2
+ stx ptr2+1
+ jsr pushax
+ jsr memcpy_upwards
;
; written += offset;
;
- lda _offset
- clc
- adc _written
- sta _written
- lda _offset+1
- adc _written+1
-L0046: sta _written+1
+ lda _offset
+ clc
+ adc _written
+ sta _written
+ lda _offset+1
+ adc _written+1
+L0046: sta _written+1
;
; while (written < outlen) {
;
- lda _written
- cmp _outlen
- lda _written+1
- sbc _outlen+1
- jcc L0004
+ lda _written
+ cmp _outlen
+ lda _written+1
+ sbc _outlen+1
+ jcc L0004
- rts
+ rts
.endproc
projects / cc65 / commitdiff