/*
* The MIT License (MIT)
*
* Copyright (c) 2019 Ha Thach for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifdef NRF52840_XXAA
#include <string.h>
#include "flash_cache.h"
#include "common_func.h"
#include "variant.h"
#include "wiring_digital.h"
//--------------------------------------------------------------------+
// MACRO TYPEDEF CONSTANT ENUM DECLARATION
//--------------------------------------------------------------------+
static inline uint32_t page_addr_of (uint32_t addr)
{
return addr & ~(FLASH_CACHE_SIZE - 1);
}
static inline uint32_t page_offset_of (uint32_t addr)
{
return addr & (FLASH_CACHE_SIZE - 1);
}
int flash_cache_write (flash_cache_t* fc, uint32_t dst, void const * src, uint32_t len)
{
uint8_t const * src8 = (uint8_t const *) src;
uint32_t remain = len;
// Program up to page boundary each loop
while ( remain )
{
uint32_t const page_addr = page_addr_of(dst);
uint32_t const offset = page_offset_of(dst);
uint32_t wr_bytes = FLASH_CACHE_SIZE - offset;
wr_bytes = min32(remain, wr_bytes);
// Page changes, flush old and update new cache
if ( page_addr != fc->cache_addr )
{
flash_cache_flush(fc);
fc->cache_addr = page_addr;
// read a whole page from flash
fc->read(fc->cache_buf, page_addr, FLASH_CACHE_SIZE);
}
memcpy(fc->cache_buf + offset, src8, wr_bytes);
// adjust for next run
src8 += wr_bytes;
remain -= wr_bytes;
dst += wr_bytes;
}
return len - remain;
}
void flash_cache_flush (flash_cache_t* fc)
{
if ( fc->cache_addr == FLASH_CACHE_INVALID_ADDR ) return;
// skip erase & program if verify() exists, and memory matches
if ( !(fc->verify && fc->verify(fc->cache_addr, fc->cache_buf, FLASH_CACHE_SIZE)) )
{
// indicator TODO allow to disable flash indicator
ledOn(LED_BUILTIN);
fc->erase(fc->cache_addr);
fc->program(fc->cache_addr, fc->cache_buf, FLASH_CACHE_SIZE);
ledOff(LED_BUILTIN);
}
fc->cache_addr = FLASH_CACHE_INVALID_ADDR;
}
int flash_cache_read (flash_cache_t* fc, void* dst, uint32_t addr, uint32_t count)
{
// there is no check for overflow / wraparound for dst + count, addr + count.
// this might be a useful thing to add for at least debug builds.
// overwrite with cache value if available
if ( (fc->cache_addr != FLASH_CACHE_INVALID_ADDR) && // cache is not valid
!(addr < fc->cache_addr && addr + count <= fc->cache_addr) && // starts before, ends before cache area
!(addr >= fc->cache_addr + FLASH_CACHE_SIZE) ) // starts after end of cache area
{
// This block is entered only when the read overlaps the cache area by at least one byte.
// If the read starts before the cache area, it's further guaranteed
// that count is large enough to cause the read to enter
// the cache area by at least 1 byte.
uint32_t dst_off = 0;
uint32_t src_off = 0;
if (addr < fc->cache_addr)
{
dst_off = fc->cache_addr - addr;
// Read the bytes prior to the cache address
fc->read(dst, addr, dst_off);
}
else
{
src_off = addr - fc->cache_addr;
}
// Thus, after the above code block executes:
// *** AT MOST ***, only one of src_off and dst_off are non-zero;
// (Both may be zero when the read starts at the start of the cache area.)
// dst_off corresponds to the number of bytes already read from PRIOR to the cache area.
// src_off corresponds to the byte offset to start reading at, from WITHIN the cache area.
// How many bytes to memcpy from flash area?
// Remember that, AT MOST, one of src_off and dst_off are non-zero.
// If src_off is non-zero, then dst_off is zero, representing that the
// read starts inside the cache. In this case:
// PARAM1 := FLASH_CACHE_SIZE - src_off == maximum possible bytes to read from cache
// PARAM2 := count
// Thus, taking the minimum of the two gives the number of bytes to read from cache,
// in the range [ 1 .. FLASH_CACHE_SIZE-src_off ].
// Else if dst_off is non-zero, then src_off is zero, representing that the
// read started prior to the cache area. In this case:
// PARAM1 := FLASH_CACHE_SIZE == full size of the cache
// PARAM2 := count - dst_off == total bytes requested, minus the count of those already read
// Because the original request is guaranteed to overlap the cache, the range for
// PARAM2 is ensured to be [ 1 .. count-1 ].
// Thus, taking the minimum of the two gives the number of bytes to read from cache,
// in the range [ 1 .. FLASH_CACHE_SIZE ]
// Else both src_off and dst_off are zero, representing that the read is starting
// exactly aligned to the cache.
// PARAM1 := FLASH_CACHE_SIZE
// PARAM2 := count
// Thus, taking the minimum of the two gives the number of bytes to read from cache,
// in the range [ 1 .. FLASH_CACHE_SIZE ]
//
// Therefore, in all cases, there is assurance that cache_bytes
// will be in the final range [1..FLASH_CACHE_SIZE].
uint32_t cache_bytes = minof(FLASH_CACHE_SIZE-src_off, count - dst_off);
// Use memcpy to read cached data into the buffer
// If src_off is non-zero, then dst_off is zero, representing that the
// read starts inside the cache. In this case:
// PARAM1 := dst
// PARAM2 := fc->cache_buf + src_off
// PARAM3 := cache_bytes
// Thus, all works as expected when starting in the midst of the cache.
// Else if dst_off is non-zero, then src_off is zero, representing that the
// read started prior to the cache. In this case:
// PARAM1 := dst + dst_off == destination offset by number of bytes already read
// PARAM2 := fc->cache_buf
// PARAM3 := cache_bytes
// Thus, all works as expected when starting prior to the cache.
// Else both src_off and dst_off are zero, representing that the read is starting
// exactly aligned to the cache.
// PARAM1 := dst
// PARAM2 := fc->cache_buf
// PARAM3 := cache_bytes
// Thus, all works as expected when starting exactly at the cache boundary
//
// Therefore, in all cases, there is assurance that cache_bytes
// will be in the final range [1..FLASH_CACHE_SIZE].
memcpy(dst + dst_off, fc->cache_buf + src_off, cache_bytes);
// Read any final bytes from flash
// As noted above, dst_off represents the count of bytes read prior to the cache
// while cache_bytes represents the count of bytes read from the cache;
// This code block is guaranteed to overlap the cache area by at least one byte.
// Thus, copied will correspond to the total bytes already copied,
// and is guaranteed to be in the range [ 1 .. count ].
uint32_t copied = dst_off + cache_bytes;
//
if ( copied < count )
{
fc->read(dst + copied, addr + copied, count - copied);
}
}
else
{
// not using the cache, so just forward to read from flash
fc->read(dst, addr, count);
}
return (int) count;
}
#endif