Add CRC10/ATM (bit reversed) table generator and evaluator

.gitignore

@@ -1,6 +1,7 @@
 *.asm
 *.o
 *.seed
+/preForth/crc10.forth
 /preForth/preForth
 /preForth/seedForth
 /preForth/__temp__.fs

preForth/Makefile

@@ -124,12 +124,13 @@ seedForth.pre \
 # a little ugly, because gforth insists upon echoing anything read from
 # stdin, and also does not allow parsing words to cross a file boundary,
 # so we will concatenate the tokenizer and source into a *.fs file first
-seedForthDemo.seed: seedForth-tokenizer.fs seedForthDemo.seedsource
+seedForthDemo.seed: crc10.forth seedForth-tokenizer.fs seedForthDemo.seedsource
 	cat $^ >__temp__.fs
 	gforth __temp__.fs -e bye >$@
 	rm __temp__.fs
 
 seedForthBoot.seed: \
+crc10.forth \
 seedForth-tokenizer.fs \
 seedForthRuntime.seedsource \
 seedForthBoot.seedsource
@@ -138,13 +139,17 @@ seedForthBoot.seedsource
 	rm __temp__.fs
 
 seedForthInteractive.seed: \
+crc10.forth \
 seedForth-tokenizer.fs \
 seedForthRuntime.seedsource \
 seedForthInteractive.seedsource
 	cat $^ >__temp__.fs
 	gforth __temp__.fs -e bye >$@
 	rm __temp__.fs
 
+crc10.forth: crc10_gen.forth
+	gforth $^ -e bye >$@
+
 .PHONY=clean
 clean:
 	rm -f *.asm *.o *.seed preForthdemo preForth seedForth __temp__.fs

preForth/crc10_gen.forth

@@ -0,0 +1,50 @@
+\ run this as follows:
+\ ./seedForth seedForthBoot.seed runtime.forth crc10_gen.forth >crc10.forth
+
+817 Constant poly \ CRC-10/ATM, truncated polynomial 0x233, bit reversed 0x331
+
+\ we don't want MS-DOS style line endings in the generated CRC table file
+: lf 10 emit ;
+
+: gen
+  ." Create crc10_tab" lf
+  256 0 ?DO
+    I 8 0 ?DO
+      \ split into LSB and the remaining bits
+      \ in seedForth: 2 u/mod swap
+      \ in gForth: 2 /mod swap
+      dup 1 rshift swap 1 and
+
+      IF poly xor THEN
+    LOOP
+    . ',' emit
+    I 7 and 7 = IF lf ELSE space THEN
+  LOOP
+  lf
+  ." : crc10 ( addr len crc -- crc )" lf
+  ."   swap 0 ?DO ( addr crc )" lf
+  ."     \ retrieve next character" lf
+  ."     over I + c@" lf
+  lf
+  ."     \ xor into low bits of crc" lf
+  ."     xor" lf
+  lf
+  ."     \ separate into table index and remaining bits" lf
+  ."     \ 256 u/mod swap" lf
+  ."     dup 8 rshift swap 255 and" lf
+  lf
+  ."     \ look up new bits from table" lf
+  ."     cells crc10_tab + @" lf
+  lf
+  ."     \ combine with remaining (shifted right) bits" lf
+  ."     xor" lf
+  ."   LOOP" lf
+  ."   nip" lf
+  ." ;" lf
+  lf
+  ." \ testing:" lf
+  ." \ Create hello 104 c, 101 c, 108 c, 108 c, 111 c," lf
+  ." \ hello 5 1023 crc10 . ;" lf
+;
+
+gen

preForth/seedForth-tokenizer

@@ -1,2 +1,2 @@
 #!/bin/sh
-./seedForth seedForthBoot.seed runtime.forth seedForth-tokenizer.fs -
+./seedForth seedForthBoot.seed runtime.forth crc10.forth seedForth-tokenizer.fs -