[ion/crc] Fix crc: n0100 does not have 8-bits hardware implementation

ion/Makefile

@@ -22,6 +22,7 @@ initializer_list = $(shell echo $(1) | sed  "s/\(.\)/'\1',/g")0
 $(call object_for,ion/src/shared/platform_info.cpp): SFLAGS += -DPATCH_LEVEL="$(call initializer_list,$(PATCH_LEVEL))" -DEPSILON_VERSION="$(call initializer_list,$(EPSILON_VERSION))"
 
 src += $(addprefix ion/src/shared/, \
+  crc32_eat_byte.cpp \
   decompress.cpp \
   events.cpp \
   led.cpp \

ion/include/ion.h

@@ -35,6 +35,8 @@ const char * fccId();
 // CRC32 : non xor-ed, non reversed, direct, polynomial 4C11DB7
 uint32_t crc32Word(const uint32_t * data, size_t length); // Only accepts whole 32bit values
 uint32_t crc32Byte(const uint8_t * data, size_t length);
+uint32_t crc32EatByte(uint32_t previousCRC, uint8_t data);
+
 
 // Provides a true random number
 uint32_t random();

ion/src/device/n0100/regs/config/crc.h

@@ -0,0 +1,6 @@
+#ifndef ION_DEVICE_N0100_REGS_CONFIG_CRC_H
+#define ION_DEVICE_N0100_REGS_CONFIG_CRC_H
+
+#define REGS_CRC_CONFIG_BYTE_ACCESS 0
+
+#endif

ion/src/device/n0110/regs/config/crc.h

@@ -0,0 +1,6 @@
+#ifndef ION_DEVICE_N0110_REGS_CONFIG_CRC_H
+#define ION_DEVICE_N0110_REGS_CONFIG_CRC_H
+
+#define REGS_CRC_CONFIG_BYTE_ACCESS 1
+
+#endif

ion/src/device/shared/drivers/crc32.cpp

@@ -6,6 +6,7 @@ namespace Ion {
 using namespace Device::Regs;
 
 uint32_t crc32Byte(const uint8_t * data, size_t length) {
+  uint32_t result = 0;
   bool initialCRCEngineState = RCC.AHB1ENR()->getCRCEN();
   RCC.AHB1ENR()->setCRCEN(true);
   CRC.CR()->setRESET(true);
@@ -18,12 +19,20 @@ uint32_t crc32Byte(const uint8_t * data, size_t length) {
     CRC.DR_WordAccess()->set(*((uint32_t *)data));
     data += 4;
   }
-  // Scanning the remaining data with byte accesses
+
+#if REGS_CRC_CONFIG_BYTE_ACCESS
+  // Scan the remaining data with byte accesses
   while (data < end) {
     CRC.DR_ByteAccess()->set(*data++);
   }
+  result = CRC.DR_WordAccess()->get();
+#else
+  result = CRC.DR_WordAccess()->get();
+  while (data < end) {
+    result = Ion::crc32EatByte(result, *data++);
+  }
+#endif
 
-  uint32_t result = CRC.DR_WordAccess()->get();
   RCC.AHB1ENR()->setCRCEN(initialCRCEngineState);
   return result;
 }

ion/src/device/shared/regs/crc.h

@@ -9,8 +9,10 @@ namespace Regs {
 
 class CRC {
 public:
+#if REGS_CRC_CONFIG_BYTE_ACCESS
   class DR_ByteAccess : public Register8 {
   };
+#endif
   class DR_WordAccess : public Register32 {
   };
 
@@ -20,7 +22,9 @@ public:
   };
 
   constexpr CRC() {};
+#if REGS_CRC_CONFIG_BYTE_ACCESS
   REGS_REGISTER_AT(DR_ByteAccess, 0x00);
+#endif
   REGS_REGISTER_AT(DR_WordAccess, 0x00);
   REGS_REGISTER_AT(CR, 0x08);
 private:

ion/src/shared/crc32.cpp

@@ -1,15 +1,5 @@
 #include <ion.h>
 
-constexpr uint32_t polynomial = 0x04C11DB7;
-
-static uint32_t crc32(uint32_t crc, uint8_t data) {
-    crc ^= data << 24;
-    for (int i=8; i--;) {
-      crc = crc & 0x80000000 ? ((crc<<1)^polynomial) : (crc << 1);
-    }
-    return crc;
-}
-
 uint32_t crc32Helper(const uint8_t * data, size_t length, bool wordAccess) {
   size_t uint32ByteLength = sizeof(uint32_t)/sizeof(uint8_t);
   uint32_t crc = 0xFFFFFFFF;
@@ -20,11 +10,11 @@ uint32_t crc32Helper(const uint8_t * data, size_t length, bool wordAccess) {
     // FIXME: Assumes little-endian byte order!
     for (int j = uint32ByteLength-1; j >= 0; j--) {
       // scan byte by byte to avoid alignment issue when building for emscripten platform
-      crc = crc32(crc, data[i*uint32ByteLength+j]);
+      crc = Ion::crc32EatByte(crc, data[i*uint32ByteLength+j]);
     }
   }
   for (int i = (int) wordLength * uint32ByteLength; i < byteLength; i++) {
-    crc = crc32(crc, data[i]);
+    crc = Ion::crc32EatByte(crc, data[i]);
   }
   return crc;
 }

ion/src/shared/crc32_eat_byte.cpp

@@ -0,0 +1,11 @@
+#include <ion.h>
+
+constexpr uint32_t polynomial = 0x04C11DB7;
+
+uint32_t Ion::crc32EatByte(uint32_t crc, uint8_t data) {
+    crc ^= data << 24;
+    for (int i=8; i--;) {
+      crc = crc & 0x80000000 ? ((crc<<1)^polynomial) : (crc << 1);
+    }
+    return crc;
+}