Adjust code for MbedCRC changes

* Make mbed_error use bitwise MbedCRC call rather than local
  implementation.
* Remove use of POLY_32BIT_REV_ANSI from LittleFS.
* Move some MbedCRC instances closer to use - construction cost is
  trivial, and visibility aids compiler optimisation.

Author: kjbracey

components/storage/blockdevice/COMPONENT_SD/SDBlockDevice.cpp

@@ -252,7 +252,7 @@ const uint32_t SDBlockDevice::_block_size = BLOCK_SIZE_HC;
 #if MBED_CONF_SD_CRC_ENABLED
 SDBlockDevice::SDBlockDevice(PinName mosi, PinName miso, PinName sclk, PinName cs, uint64_t hz, bool crc_on)
     : _sectors(0), _spi(mosi, miso, sclk), _cs(cs), _is_initialized(0),
-      _init_ref_count(0), _crc_on(crc_on), _crc16(0, 0, false, false)
+      _init_ref_count(0), _crc_on(crc_on)
 #else
 SDBlockDevice::SDBlockDevice(PinName mosi, PinName miso, PinName sclk, PinName cs, uint64_t hz, bool crc_on)
     : _sectors(0), _spi(mosi, miso, sclk), _cs(cs), _is_initialized(0),
@@ -678,10 +678,11 @@ uint8_t SDBlockDevice::_cmd_spi(SDBlockDevice::cmdSupported cmd, uint32_t arg)
     cmdPacket[4] = (arg >> 0);
 
 #if MBED_CONF_SD_CRC_ENABLED
-    uint32_t crc;
     if (_crc_on) {
-        _crc7.compute((void *)cmdPacket, 5, &crc);
-        cmdPacket[5] = (char)(crc | 0x01);
+        MbedCRC<POLY_7BIT_SD, 7> crc7;
+        uint32_t crc;
+        crc7.compute(cmdPacket, 5, &crc);
+        cmdPacket[5] = ((uint8_t) crc << 1) | 0x01;
     } else
 #endif
     {
@@ -899,12 +900,13 @@ int SDBlockDevice::_read_bytes(uint8_t *buffer, uint32_t length)
 
 #if MBED_CONF_SD_CRC_ENABLED
     if (_crc_on) {
+        mbed::MbedCRC<POLY_16BIT_CCITT, 16> crc16(0, 0, false, false);
         uint32_t crc_result;
         // Compute and verify checksum
-        _crc16.compute((void *)buffer, length, &crc_result);
-        if ((uint16_t)crc_result != crc) {
-            debug_if(SD_DBG, "_read_bytes: Invalid CRC received 0x%" PRIx16 " result of computation 0x%" PRIx16 "\n",
-                     crc, (uint16_t)crc_result);
+        crc16.compute(buffer, length, &crc_result);
+        if (crc_result != crc) {
+            debug_if(SD_DBG, "_read_bytes: Invalid CRC received 0x%" PRIx16 " result of computation 0x%" PRIx32 "\n",
+                     crc, crc_result);
             _deselect();
             return SD_BLOCK_DEVICE_ERROR_CRC;
         }
@@ -934,9 +936,10 @@ int SDBlockDevice::_read(uint8_t *buffer, uint32_t length)
 
 #if MBED_CONF_SD_CRC_ENABLED
     if (_crc_on) {
+        mbed::MbedCRC<POLY_16BIT_CCITT, 16> crc16(0, 0, false, false);
         uint32_t crc_result;
         // Compute and verify checksum
-        _crc16.compute((void *)buffer, length, &crc_result);
+        crc16.compute((void *)buffer, length, &crc_result);
         if ((uint16_t)crc_result != crc) {
             debug_if(SD_DBG, "_read_bytes: Invalid CRC received 0x%" PRIx16 " result of computation 0x%" PRIx16 "\n",
                      crc, (uint16_t)crc_result);
@@ -962,8 +965,9 @@ uint8_t SDBlockDevice::_write(const uint8_t *buffer, uint8_t token, uint32_t len
 
 #if MBED_CONF_SD_CRC_ENABLED
     if (_crc_on) {
+        mbed::MbedCRC<POLY_16BIT_CCITT, 16> crc16(0, 0, false, false);
         // Compute CRC
-        _crc16.compute((void *)buffer, length, &crc);
+        crc16.compute(buffer, length, &crc);
     }
 #endif
 

components/storage/blockdevice/COMPONENT_SD/SDBlockDevice.h

@@ -256,8 +256,6 @@ class SDBlockDevice : public mbed::BlockDevice {
 
 #if MBED_CONF_SD_CRC_ENABLED
     bool _crc_on;
-    mbed::MbedCRC<POLY_7BIT_SD, 7> _crc7;
-    mbed::MbedCRC<POLY_16BIT_CCITT, 16> _crc16;
 #endif
 };
 

drivers/source/MbedCRC.cpp

@@ -146,3 +146,11 @@ const uint32_t MbedCRC<POLY_32BIT_ANSI, 32, CrcMode::TABLE>::_crc_table[MBED_CRC
 #endif // MBED_CRC_TABLE_SIZE > 0
 
 } // namespace mbed
+
+extern "C" uint32_t mbed_tiny_compute_crc32(const void *data, int datalen)
+{
+    mbed::MbedCRC<POLY_32BIT_ANSI, 32, mbed::CrcMode::BITWISE> crc32(0, 0, false, false);
+    uint32_t result;
+    crc32.compute(data, datalen, &result);
+    return result;
+}

features/storage/filesystem/littlefs/LittleFileSystem.cpp

@@ -25,8 +25,10 @@ namespace mbed {
 extern "C" void lfs_crc(uint32_t *crc, const void *buffer, size_t size)
 {
     uint32_t initial_xor = *crc;
-    MbedCRC<POLY_32BIT_REV_ANSI, 32> ct(initial_xor, 0x0, true, false);
-    ct.compute((void *)buffer, size, (uint32_t *) crc);
+    // lfs_cache_crc calls lfs_crc for every byte individually, so can't afford
+    // start-up overhead for hardware acceleration. Limit to table-based.
+    MbedCRC<POLY_32BIT_ANSI, 32, CrcMode::TABLE> ct(initial_xor, 0x0, true, true);
+    ct.compute(buffer, size, crc);
 }
 
 ////// Conversion functions //////

features/storage/kvstore/direct_access_devicekey/DirectAccessDevicekey.cpp

@@ -308,7 +308,7 @@ static uint32_t calc_crc(uint32_t init_crc, uint32_t data_size, const void *data
 {
     uint32_t crc;
     MbedCRC<POLY_32BIT_ANSI, 32> ct(init_crc, 0x0, true, false);
-    ct.compute(const_cast<void *>(data_buf), data_size, &crc);
+    ct.compute(data_buf, data_size, &crc);
     return crc;
 }
 #endif // DEVICE_FLASH

features/storage/kvstore/tdbstore/TDBStore.cpp

@@ -117,7 +117,7 @@ static uint32_t calc_crc(uint32_t init_crc, uint32_t data_size, const void *data
 {
     uint32_t crc;
     MbedCRC<POLY_32BIT_ANSI, 32> ct(init_crc, 0x0, true, false);
-    ct.compute(const_cast<void *>(data_buf), data_size, &crc);
+    ct.compute(data_buf, data_size, &crc);
     return crc;
 }
 

platform/source/mbed_error.c

@@ -27,6 +27,7 @@
 #include "platform/mbed_power_mgmt.h"
 #include "platform/mbed_stats.h"
 #include "platform/source/TARGET_CORTEX_M/mbed_fault_handler.h"
+#include "drivers/MbedCRC.h"
 #include "mbed_rtx.h"
 #ifdef MBED_CONF_RTOS_PRESENT
 #include "rtx_os.h"
@@ -64,36 +65,6 @@ static mbed_error_status_t handle_error(mbed_error_status_t error_status, unsign
 //Global for populating the context in exception handler
 static mbed_error_ctx *const report_error_ctx = (mbed_error_ctx *)(ERROR_CONTEXT_LOCATION);
 static bool is_reboot_error_valid = false;
-
-//Helper function to calculate CRC
-//NOTE: It would have been better to use MbedCRC implementation. But
-//MbedCRC uses table based calculation and we dont want to keep that table memory
-//used up for this purpose. Also we cannot force bitwise calculation in MbedCRC
-//and it also requires a new wrapper to be called from C implementation. Since
-//we dont have many uses cases to create a C wrapper for MbedCRC and the data
-//we calculate CRC on in this context is very less we will use a local
-//implementation here.
-static unsigned int compute_crc32(const void *data, int datalen)
-{
-    const unsigned int polynomial = 0x04C11DB7; /* divisor is 32bit */
-    unsigned int crc = 0; /* CRC value is 32bit */
-    unsigned char *buf = (unsigned char *)data;//use a temp variable to make code readable and to avoid typecasting issues.
-
-    for (; datalen > 0; datalen--) {
-        unsigned char b = *buf++;
-        crc ^= (unsigned int)(b << 24); /* move byte into upper 8bit */
-        for (int i = 0; i < 8; i++) {
-            /* is MSB 1 */
-            if ((crc & 0x80000000) != 0) {
-                crc = (unsigned int)((crc << 1) ^ polynomial);
-            } else {
-                crc <<= 1;
-            }
-        }
-    }
-
-    return crc;
-}
 #endif
 
 //Helper function to halt the system
@@ -246,7 +217,7 @@ mbed_error_status_t mbed_error_initialize(void)
 
     //Just check if we have valid value for error_status, if error_status is positive(which is not valid), no need to check crc
     if (report_error_ctx->error_status < 0) {
-        crc_val = compute_crc32(report_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
+        crc_val = mbed_tiny_compute_crc32(report_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
         //Read report_error_ctx and check if CRC is correct, and with valid status code
         if ((report_error_ctx->crc_error_ctx == crc_val) && (report_error_ctx->is_error_processed == 0)) {
             is_reboot_error_valid = true;
@@ -258,7 +229,7 @@ mbed_error_status_t mbed_error_initialize(void)
             if (report_error_ctx->error_reboot_count > 0) {
 
                 report_error_ctx->is_error_processed = 1;//Set the flag that we already processed this error
-                crc_val = compute_crc32(report_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
+                crc_val = mbed_tiny_compute_crc32(report_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
                 report_error_ctx->crc_error_ctx = crc_val;
 
                 //Enforce max-reboot only if auto reboot is enabled
@@ -321,7 +292,7 @@ WEAK MBED_NORETURN mbed_error_status_t mbed_error(mbed_error_status_t error_stat
 
 #if MBED_CONF_PLATFORM_CRASH_CAPTURE_ENABLED
     uint32_t crc_val = 0;
-    crc_val = compute_crc32(report_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
+    crc_val = mbed_tiny_compute_crc32(report_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
     //Read report_error_ctx and check if CRC is correct for report_error_ctx
     if (report_error_ctx->crc_error_ctx == crc_val) {
         uint32_t current_reboot_count = report_error_ctx->error_reboot_count;
@@ -331,7 +302,7 @@ WEAK MBED_NORETURN mbed_error_status_t mbed_error(mbed_error_status_t error_stat
     }
     last_error_ctx.is_error_processed = 0;//Set the flag that this is a new error
     //Update the struct with crc
-    last_error_ctx.crc_error_ctx = compute_crc32(&last_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
+    last_error_ctx.crc_error_ctx = mbed_tiny_compute_crc32(&last_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
     //Protect report_error_ctx while we update it
     core_util_critical_section_enter();
     memcpy(report_error_ctx, &last_error_ctx, sizeof(mbed_error_ctx));
@@ -384,7 +355,7 @@ mbed_error_status_t mbed_reset_reboot_count()
         core_util_critical_section_enter();
         report_error_ctx->error_reboot_count = 0;//Set reboot count to 0
         //Update CRC
-        crc_val = compute_crc32(report_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
+        crc_val = mbed_tiny_compute_crc32(report_error_ctx, offsetof(mbed_error_ctx, crc_error_ctx));
         report_error_ctx->crc_error_ctx = crc_val;
         core_util_critical_section_exit();
         return MBED_SUCCESS;