Diff: spiffs_cache.c

Revision:

0:bb4e812f7c97

Child:

3:9adcf49bb77d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spiffs_cache.c	Tue Dec 16 15:13:10 2014 +0000
@@ -0,0 +1,301 @@
+/*
+ * spiffs_cache.c
+ *
+ *  Created on: Jun 23, 2013
+ *      Author: petera
+ */
+
+#include "spiffs.h"
+#include "spiffs_nucleus.h"
+
+#if SPIFFS_CACHE
+
+// returns cached page for give page index, or null if no such cached page
+static spiffs_cache_page *spiffs_cache_page_get(spiffs *fs, spiffs_page_ix pix) {
+  spiffs_cache *cache = spiffs_get_cache(fs);
+  if ((cache->cpage_use_map & cache->cpage_use_mask) == 0) return 0;
+  int i;
+  for (i = 0; i < cache->cpage_count; i++) {
+    spiffs_cache_page *cp = spiffs_get_cache_page_hdr(fs, cache, i);
+    if ((cache->cpage_use_map & (1<<i)) &&
+        (cp->flags & SPIFFS_CACHE_FLAG_TYPE_WR) == 0 &&
+        cp->pix == pix ) {
+      SPIFFS_CACHE_DBG("CACHE_GET: have cache page %i for %04x\n", i, pix);
+      cp->last_access = cache->last_access;
+      return cp;
+    }
+  }
+  //SPIFFS_CACHE_DBG("CACHE_GET: no cache for %04x\n", pix);
+  return 0;
+}
+
+// frees cached page
+static s32_t spiffs_cache_page_free(spiffs *fs, int ix, u8_t write_back) {
+  s32_t res = SPIFFS_OK;
+  spiffs_cache *cache = spiffs_get_cache(fs);
+  spiffs_cache_page *cp = spiffs_get_cache_page_hdr(fs, cache, ix);
+  if (cache->cpage_use_map & (1<<ix)) {
+    if (write_back &&
+        (cp->flags & SPIFFS_CACHE_FLAG_TYPE_WR) == 0 &&
+        (cp->flags & SPIFFS_CACHE_FLAG_DIRTY)) {
+      u8_t *mem =  spiffs_get_cache_page(fs, cache, ix);
+      res = fs->cfg.hal_write_f(SPIFFS_PAGE_TO_PADDR(fs, cp->pix), SPIFFS_CFG_LOG_PAGE_SZ(fs), mem);
+    }
+
+    cp->flags = 0;
+    cache->cpage_use_map &= ~(1 << ix);
+
+    if (cp->flags & SPIFFS_CACHE_FLAG_TYPE_WR) {
+      SPIFFS_CACHE_DBG("CACHE_FREE: free cache page %i objid %04x\n", ix, cp->obj_id);
+    } else {
+      SPIFFS_CACHE_DBG("CACHE_FREE: free cache page %i pix %04x\n", ix, cp->pix);
+    }
+  }
+
+  return res;
+}
+
+// removes the oldest accessed cached page
+static s32_t spiffs_cache_page_remove_oldest(spiffs *fs, u8_t flag_mask, u8_t flags) {
+  s32_t res = SPIFFS_OK;
+  spiffs_cache *cache = spiffs_get_cache(fs);
+
+  if ((cache->cpage_use_map & cache->cpage_use_mask) != cache->cpage_use_mask) {
+    // at least one free cpage
+    return SPIFFS_OK;
+  }
+
+  // all busy, scan thru all to find the cpage which has oldest access
+  int i;
+  int cand_ix = -1;
+  u32_t oldest_val = 0;
+  for (i = 0; i < cache->cpage_count; i++) {
+    spiffs_cache_page *cp = spiffs_get_cache_page_hdr(fs, cache, i);
+    if ((cache->last_access - cp->last_access) > oldest_val &&
+        (cp->flags & flag_mask) == flags) {
+      oldest_val = cache->last_access - cp->last_access;
+      cand_ix = i;
+    }
+  }
+
+  if (cand_ix >= 0) {
+    res = spiffs_cache_page_free(fs, cand_ix, 1);
+  }
+
+  return res;
+}
+
+// allocates a new cached page and returns it, or null if all cache pages are busy
+static spiffs_cache_page *spiffs_cache_page_allocate(spiffs *fs) {
+  spiffs_cache *cache = spiffs_get_cache(fs);
+  if (cache->cpage_use_map == 0xffffffff) {
+    // out of cache memory
+    return 0;
+  }
+  int i;
+  for (i = 0; i < cache->cpage_count; i++) {
+    if ((cache->cpage_use_map & (1<<i)) == 0) {
+      spiffs_cache_page *cp = spiffs_get_cache_page_hdr(fs, cache, i);
+      cache->cpage_use_map |= (1<<i);
+      cp->last_access = cache->last_access;
+      SPIFFS_CACHE_DBG("CACHE_ALLO: allocated cache page %i\n", i);
+      return cp;
+    }
+  }
+  // out of cache entries
+  return 0;
+}
+
+// drops the cache page for give page index
+void spiffs_cache_drop_page(spiffs *fs, spiffs_page_ix pix) {
+  spiffs_cache_page *cp =  spiffs_cache_page_get(fs, pix);
+  if (cp) {
+    spiffs_cache_page_free(fs, cp->ix, 0);
+  }
+}
+
+// ------------------------------
+
+// reads from spi flash or the cache
+s32_t spiffs_phys_rd(
+    spiffs *fs,
+    u8_t op,
+    spiffs_file fh,
+    u32_t addr,
+    u32_t len,
+    u8_t *dst) {
+  s32_t res = SPIFFS_OK;
+  spiffs_cache *cache = spiffs_get_cache(fs);
+  spiffs_cache_page *cp =  spiffs_cache_page_get(fs, SPIFFS_PADDR_TO_PAGE(fs, addr));
+  cache->last_access++;
+  if (cp) {
+#if SPIFFS_CACHE_STATS
+    fs->cache_hits++;
+#endif
+    cp->last_access = cache->last_access;
+  } else {
+    if ((op & SPIFFS_OP_TYPE_MASK) == SPIFFS_OP_T_OBJ_LU2) {
+      // for second layer lookup functions, we do not cache in order to prevent shredding
+      return fs->cfg.hal_read_f(
+          addr ,
+          len,
+          dst);
+    }
+#if SPIFFS_CACHE_STATS
+    fs->cache_misses++;
+#endif
+    res = spiffs_cache_page_remove_oldest(fs, SPIFFS_CACHE_FLAG_TYPE_WR, 0);
+    cp = spiffs_cache_page_allocate(fs);
+    if (cp) {
+      cp->flags = SPIFFS_CACHE_FLAG_WRTHRU;
+      cp->pix = SPIFFS_PADDR_TO_PAGE(fs, addr);
+    }
+
+    s32_t res2 = fs->cfg.hal_read_f(
+        addr - SPIFFS_PADDR_TO_PAGE_OFFSET(fs, addr),
+        SPIFFS_CFG_LOG_PAGE_SZ(fs),
+        spiffs_get_cache_page(fs, cache, cp->ix));
+    if (res2 != SPIFFS_OK) {
+      res = res2;
+    }
+  }
+  u8_t *mem =  spiffs_get_cache_page(fs, cache, cp->ix);
+  memcpy(dst, &mem[SPIFFS_PADDR_TO_PAGE_OFFSET(fs, addr)], len);
+  return res;
+}
+
+// writes to spi flash and/or the cache
+s32_t spiffs_phys_wr(
+    spiffs *fs,
+    u8_t op,
+    spiffs_file fh,
+    u32_t addr,
+    u32_t len,
+    u8_t *src) {
+  spiffs_page_ix pix = SPIFFS_PADDR_TO_PAGE(fs, addr);
+  spiffs_cache *cache = spiffs_get_cache(fs);
+  spiffs_cache_page *cp =  spiffs_cache_page_get(fs, pix);
+
+  if (cp && (op & SPIFFS_OP_COM_MASK) != SPIFFS_OP_C_WRTHRU) {
+    // have a cache page
+    // copy in data to cache page
+
+    if ((op & SPIFFS_OP_COM_MASK) == SPIFFS_OP_C_DELE &&
+        (op & SPIFFS_OP_TYPE_MASK) != SPIFFS_OP_T_OBJ_LU) {
+      // page is being deleted, wipe from cache - unless it is a lookup page
+      spiffs_cache_page_free(fs, cp->ix, 0);
+      return fs->cfg.hal_write_f(addr, len, src);
+    }
+
+    u8_t *mem =  spiffs_get_cache_page(fs, cache, cp->ix);
+    memcpy(&mem[SPIFFS_PADDR_TO_PAGE_OFFSET(fs, addr)], src, len);
+
+    cache->last_access++;
+    cp->last_access = cache->last_access;
+
+    if (cp->flags && SPIFFS_CACHE_FLAG_WRTHRU) {
+      // page is being updated, no write-cache, just pass thru
+      return fs->cfg.hal_write_f(addr, len, src);
+    } else {
+      return SPIFFS_OK;
+    }
+  } else {
+    // no cache page, no write cache - just write thru
+    return fs->cfg.hal_write_f(addr, len, src);
+  }
+}
+
+#if SPIFFS_CACHE_WR
+// returns the cache page that this fd refers, or null if no cache page
+spiffs_cache_page *spiffs_cache_page_get_by_fd(spiffs *fs, spiffs_fd *fd) {
+  spiffs_cache *cache = spiffs_get_cache(fs);
+
+  if ((cache->cpage_use_map & cache->cpage_use_mask) == 0) {
+    // all cpages free, no cpage cannot be assigned to obj_id
+    return 0;
+  }
+
+  int i;
+  for (i = 0; i < cache->cpage_count; i++) {
+    spiffs_cache_page *cp = spiffs_get_cache_page_hdr(fs, cache, i);
+    if ((cache->cpage_use_map & (1<<i)) &&
+        (cp->flags & SPIFFS_CACHE_FLAG_TYPE_WR) &&
+        cp->obj_id == fd->obj_id) {
+      return cp;
+    }
+  }
+
+  return 0;
+}
+
+// allocates a new cache page and refers this to given fd - flushes an old cache
+// page if all cache is busy
+spiffs_cache_page *spiffs_cache_page_allocate_by_fd(spiffs *fs, spiffs_fd *fd) {
+  // before this function is called, it is ensured that there is no already existing
+  // cache page with same object id
+  spiffs_cache_page_remove_oldest(fs, SPIFFS_CACHE_FLAG_TYPE_WR, 0);
+  spiffs_cache_page *cp = spiffs_cache_page_allocate(fs);
+  if (cp == 0) {
+    // could not get cache page
+    return 0;
+  }
+
+  cp->flags = SPIFFS_CACHE_FLAG_TYPE_WR;
+  cp->obj_id = fd->obj_id;
+  fd->cache_page = cp;
+  return cp;
+}
+
+// unrefers all fds that this cache page refers to and releases the cache page
+void spiffs_cache_fd_release(spiffs *fs, spiffs_cache_page *cp) {
+  if (cp == 0) return;
+  int i;
+  spiffs_fd *fds = (spiffs_fd *)fs->fd_space;
+  for (i = 0; i < fs->fd_count; i++) {
+    spiffs_fd *cur_fd = &fds[i];
+    if (cur_fd->file_nbr != 0 && cur_fd->cache_page == cp) {
+      cur_fd->cache_page = 0;
+    }
+  }
+  spiffs_cache_page_free(fs, cp->ix, 0);
+
+  cp->obj_id = 0;
+}
+
+#endif
+
+// initializes the cache
+void spiffs_cache_init(spiffs *fs) {
+  if (fs->cache == 0) return;
+  u32_t sz = fs->cache_size;
+  u32_t cache_mask = 0;
+  int i;
+  int cache_entries =
+      (sz - sizeof(spiffs_cache)) / (SPIFFS_CACHE_PAGE_SIZE(fs));
+  if (cache_entries <= 0) return;
+
+  for (i = 0; i < cache_entries; i++) {
+    cache_mask <<= 1;
+    cache_mask |= 1;
+  }
+
+  spiffs_cache cache;
+  memset(&cache, 0, sizeof(spiffs_cache));
+  cache.cpage_count = cache_entries;
+  cache.cpages = (u8_t *)(fs->cache + sizeof(spiffs_cache));
+
+  cache.cpage_use_map = 0xffffffff;
+  cache.cpage_use_mask = cache_mask;
+  memcpy(fs->cache, &cache, sizeof(spiffs_cache));
+
+  spiffs_cache *c = spiffs_get_cache(fs);
+
+  memset(c->cpages, 0, c->cpage_count * SPIFFS_CACHE_PAGE_SIZE(fs));
+
+  c->cpage_use_map &= ~(c->cpage_use_mask);
+  for (i = 0; i < cache.cpage_count; i++) {
+    spiffs_get_cache_page_hdr(fs, c, i)->ix = i;
+  }
+}
+
+#endif // SPIFFS_CACHE
\ No newline at end of file