Add CRC32 implementation

6 files changed, 124 insertions, 2 deletions

diff --git a/prototype/fw/Makefile b/prototype/fw/Makefile
index db7952b..3fbd029 100644
--- a/prototype/fw/Makefile
+++ b/prototype/fw/Makefile
@@ -23,9 +23,9 @@ DEBUG			?= 1
 OPT				?= 0
 
 BUILDDIR 		?= build
-BINARY 			:= safetyreset.elf
+BINARY 			:= rotohsm_proto_rotor.elf
 LDSCRIPT 		:= generic_stm32.ld
-DEVICE 			:= STM32F302C8
+DEVICE 			:= STM32F302CB
 
 
 ########################################################################################################################
@@ -53,6 +53,7 @@ C_SOURCES += $(MUSL_SOURCES)
 
 PREFIX		?= arm-none-eabi-
 
+HOSTCC		:= gcc
 CC			:= $(PREFIX)gcc
 CPP			:= $(PREFIX)cpp
 CXX			:= $(PREFIX)g++
@@ -102,6 +103,8 @@ COMMON_CFLAGS	+= -O$(OPT) -std=gnu11 -g
 COMMON_CFLAGS 	+= $(DEVICE_DEFINES)
 COMMON_CFLAGS 	+= -DDEBUG=$(DEBUG)
 
+HOST_CFLAGS		+= $(COMMON_CFLAGS)
+
 # for musl
 CFLAGS			+= -Dhidden=
 
@@ -193,6 +196,13 @@ $(BUILDDIR)/%.o: %.s
 	mkdir -p $(@D)
 	$(CC) $(COMMON_CFLAGS) $(CFLAGS) $(EXT_CFLAGS) -o $@ -c $<
 
+$(BUILDDIR)/crc32_test: src/crc32_test.c src/crc32.c
+	$(HOSTCC) $(HOST_CFLAGS) -o $@ $^
+
+.PHONY: run_tests
+run_tests: $(BUILDDIR)/crc32_test
+	$(PYTHON3) -m unittest test.crc32_ref
+
 venv:
 	test -d venv || python3 -m venv --system-site-packages venv
 	source venv/bin/activate && pip install cxxfilt pyelftools libarchive matplotlib
diff --git a/prototype/fw/src/crc32.c b/prototype/fw/src/crc32.c
new file mode 100644
index 0000000..4b03fbb
--- /dev/null
+++ b/prototype/fw/src/crc32.c
@@ -0,0 +1,35 @@
+#include "crc32.h"
+#include <unistd.h>
+
+/* Polynomial: 0xEDB88320 */
+
+/* python3:
+ * In [26]: apply = lambda st: ((st>>1) ^ 0xEDB88320) if (st & 1) else (st>>1)
+ * In [27]: print(',\n'.join([ '0x{:08x}'.format(apply(apply(apply(apply(x))))) for x in range(16) ]))
+ */
+uint32_t crc32_table[16] = {
+	0x00000000,
+	0x1db71064,
+	0x3b6e20c8,
+	0x26d930ac,
+	0x76dc4190,
+	0x6b6b51f4,
+	0x4db26158,
+	0x5005713c,
+	0xedb88320,
+	0xf00f9344,
+	0xd6d6a3e8,
+	0xcb61b38c,
+	0x9b64c2b0,
+	0x86d3d2d4,
+	0xa00ae278,
+	0xbdbdf21c
+};
+
+crc32_t crc32_update(crc32_t state, uint8_t c)
+{
+	state ^= c;
+	state = (state>>4) ^ crc32_table[state&0xf];
+	state = (state>>4) ^ crc32_table[state&0xf];
+	return state;
+}
diff --git a/prototype/fw/src/crc32.h b/prototype/fw/src/crc32.h
new file mode 100644
index 0000000..7a3a729
--- /dev/null
+++ b/prototype/fw/src/crc32.h
@@ -0,0 +1,12 @@
+#ifndef __CRC_32_H__
+#define __CRC_32_H__
+
+#include <stdint.h>
+
+typedef uint32_t crc32_t;
+
+inline static uint32_t crc32_reset() { return ~0; }
+uint32_t crc32_update(uint32_t old_state, uint8_t c);
+inline static uint32_t crc32_finalize(uint32_t state) { return ~state; }
+
+#endif /* __CRC_32_H__ */
diff --git a/prototype/fw/src/crc32_test.c b/prototype/fw/src/crc32_test.c
new file mode 100644
index 0000000..e23bb37
--- /dev/null
+++ b/prototype/fw/src/crc32_test.c
@@ -0,0 +1,20 @@
+
+#include <stdio.h>
+
+#include "crc32.h"
+
+int main(void) {
+	crc32_t state = crc32_reset();
+
+	do {
+		char c;
+		if (fread(&c, 1, 1, stdin) != 1)
+			break;
+
+		state = crc32_update(state, (uint8_t)c);
+	} while(23);
+
+	state = crc32_finalize(state);
+	printf("%08x\n", state);
+	return 0;
+}
diff --git a/prototype/fw/test/crc32_ref.py b/prototype/fw/test/crc32_ref.py
new file mode 100644
index 0000000..7ac0582
--- /dev/null
+++ b/prototype/fw/test/crc32_ref.py
@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+
+import subprocess
+import zlib
+import os
+import itertools
+import unittest
+
+INTERESTING = bytes([0x00, 0x42, 0xff, 0x01, 0x80])
+
+class RefdataTest(unittest.TestCase):
+    def run_test(self, test_data):
+        ref_val = zlib.crc32(test_data)
+
+        binary = os.environ.get('CRC32_TEST_BINARY', 'build/crc32_test')
+        
+        output = subprocess.check_output(binary, input=test_data)
+        test_val = int(output, 16) & 0xffffffff
+
+        self.assertEqual(test_val, ref_val, f'mismatched results checking input {test_data}')
+
+    def test_empty(self):
+        self.run_test(b'')
+
+    def test_one_byte(self):
+        for x in range(256):
+            self.run_test(bytes([x]))
+
+    def test_two_byte(self):
+        for x, y in itertools.product(INTERESTING, repeat=2):
+            self.run_test(bytes([x, y]))
+
+    def test_three_bytes(self):
+        for x, y, z in itertools.product(INTERESTING, repeat=3):
+            self.run_test(bytes([x, y, z]))
+
+    def test_four_bytes(self):
+        for w, x, y, z in itertools.product(INTERESTING, repeat=4):
+            self.run_test(bytes([w, x, y, z]))
+
+    def test_random_strings(self):
+        for length in range(3, 24):
+            for i in range(20):
+                self.run_test(os.urandom(length))
+
diff --git a/prototype/fw/upstream/PyCortexMDebug b/prototype/fw/upstream/PyCortexMDebug
new file mode 160000
+Subproject 77e9717a0e7c5b44214bdf70fbddf376cf2e8a7