-;\r
-; Piotr Fusik, 14.11.2001\r
-;\r
-; unsigned long __fastcall__ crc32 (unsigned long crc, unsigned char* buf,\r
-; unsigned len);\r
-;\r
-\r
- .export _crc32\r
-\r
- .import compleax, incsp2, incsp4, popax, popeax\r
- .importzp sreg, ptr1, ptr2, tmp1, tmp2\r
-\r
-POLYNOMIAL = $EDB88320\r
-\r
-make_table:\r
- ldx #0\r
-@L1: lda #0\r
- sta tmp2\r
- sta sreg\r
- sta sreg+1\r
- ldy #8\r
- txa\r
-@L2: sta tmp1\r
- lsr a\r
- bcc @L3\r
- lda sreg+1\r
- lsr a\r
- eor #(POLYNOMIAL>>24)&$FF\r
- sta sreg+1\r
- lda sreg\r
- ror a\r
- eor #(POLYNOMIAL>>16)&$FF\r
- sta sreg\r
- lda tmp2\r
- ror a\r
- eor #(POLYNOMIAL>>8)&$FF\r
- sta tmp2\r
- lda tmp1\r
- ror a\r
- eor #POLYNOMIAL&$FF\r
- bcs @L4 ; branch always\r
-@L3: rol a\r
- lsr sreg+1\r
- ror sreg\r
- ror tmp2\r
- ror a\r
-@L4: dey\r
- bne @L2\r
- sta table_0,x\r
- lda tmp2\r
- sta table_1,x\r
- lda sreg\r
- sta table_2,x\r
- lda sreg+1\r
- sta table_3,x\r
- inx\r
- bne @L1\r
- inc table_initialised\r
-RET:\r
- rts\r
-\r
-_crc32:\r
-; ptr2 = (len & 0xff) == 0 ? len : len + 0x100;\r
- tay\r
- beq @L1\r
- inx\r
-@L1: sta ptr2\r
- stx ptr2+1\r
-; ptr1 = buf\r
- jsr popax\r
- sta ptr1\r
- stx ptr1+1\r
-; if (buf == NULL) return 0;\r
- ora ptr1+1\r
- beq @L0\r
-; if (!tables_initialised) make_tables();\r
- lda table_initialised\r
- bne @dont_make\r
- jsr make_table\r
-@dont_make:\r
-; eax = crc\r
- jsr popeax\r
-; if (len == 0) return crc;\r
- ldy ptr2\r
- bne @L2\r
- ldy ptr2+1\r
- beq RET\r
-@L2:\r
-; eax = ~crc\r
- jsr compleax\r
- stx tmp2\r
- ldy #0\r
-; crc = (crc >> 8) ^ table[(crc & 0xff) ^ *p++];\r
-@L3: eor (ptr1),y\r
- tax\r
- lda table_0,x\r
- eor tmp2\r
- sta tmp1\r
- lda table_1,x\r
- eor sreg\r
- sta tmp2\r
- lda table_2,x\r
- eor sreg+1\r
- sta sreg\r
- lda table_3,x\r
- sta sreg+1\r
- lda tmp1\r
- iny\r
- bne @L4\r
- inc ptr1+1\r
-@L4: dec ptr2\r
- bne @L3\r
- dec ptr2+1\r
- bne @L3\r
- ldx tmp2\r
- jmp compleax\r
-\r
-; return 0L\r
-@L0: sta sreg\r
- sta sreg+1\r
-; ignore crc\r
- jmp incsp4\r
-\r
- .data\r
-table_initialised:\r
- .byte 0\r
-\r
- .bss\r
-table_0: .res 256\r
-table_1: .res 256\r
-table_2: .res 256\r
-table_3: .res 256\r
-\r
-\r
+;
+; Piotr Fusik, 14.11.2001
+;
+; unsigned long __fastcall__ crc32 (unsigned long crc, unsigned char* buf,
+; unsigned len);
+;
+
+ .export _crc32
+
+ .import compleax, incsp2, incsp4, popax, popeax
+ .importzp sreg, ptr1, ptr2, tmp1, tmp2
+
+POLYNOMIAL = $EDB88320
+
+make_table:
+ ldx #0
+@L1: lda #0
+ sta tmp2
+ sta sreg
+ sta sreg+1
+ ldy #8
+ txa
+@L2: sta tmp1
+ lsr a
+ bcc @L3
+ lda sreg+1
+ lsr a
+ eor #(POLYNOMIAL>>24)&$FF
+ sta sreg+1
+ lda sreg
+ ror a
+ eor #(POLYNOMIAL>>16)&$FF
+ sta sreg
+ lda tmp2
+ ror a
+ eor #(POLYNOMIAL>>8)&$FF
+ sta tmp2
+ lda tmp1
+ ror a
+ eor #POLYNOMIAL&$FF
+ bcs @L4 ; branch always
+@L3: rol a
+ lsr sreg+1
+ ror sreg
+ ror tmp2
+ ror a
+@L4: dey
+ bne @L2
+ sta table_0,x
+ lda tmp2
+ sta table_1,x
+ lda sreg
+ sta table_2,x
+ lda sreg+1
+ sta table_3,x
+ inx
+ bne @L1
+ inc table_initialised
+RET:
+ rts
+
+_crc32:
+; ptr2 = (len & 0xff) == 0 ? len : len + 0x100;
+ tay
+ beq @L1
+ inx
+@L1: sta ptr2
+ stx ptr2+1
+; ptr1 = buf
+ jsr popax
+ sta ptr1
+ stx ptr1+1
+; if (buf == NULL) return 0;
+ ora ptr1+1
+ beq @L0
+; if (!tables_initialised) make_tables();
+ lda table_initialised
+ bne @dont_make
+ jsr make_table
+@dont_make:
+; eax = crc
+ jsr popeax
+; if (len == 0) return crc;
+ ldy ptr2
+ bne @L2
+ ldy ptr2+1
+ beq RET
+@L2:
+; eax = ~crc
+ jsr compleax
+ stx tmp2
+ ldy #0
+; crc = (crc >> 8) ^ table[(crc & 0xff) ^ *p++];
+@L3: eor (ptr1),y
+ tax
+ lda table_0,x
+ eor tmp2
+ sta tmp1
+ lda table_1,x
+ eor sreg
+ sta tmp2
+ lda table_2,x
+ eor sreg+1
+ sta sreg
+ lda table_3,x
+ sta sreg+1
+ lda tmp1
+ iny
+ bne @L4
+ inc ptr1+1
+@L4: dec ptr2
+ bne @L3
+ dec ptr2+1
+ bne @L3
+ ldx tmp2
+ jmp compleax
+
+; return 0L
+@L0: sta sreg
+ sta sreg+1
+; ignore crc
+ jmp incsp4
+
+ .data
+table_initialised:
+ .byte 0
+
+ .bss
+table_0: .res 256
+table_1: .res 256
+table_2: .res 256
+table_3: .res 256
+
+
projects / cc65 / blobdiff