NAND Flash memory emulation and ECC calculation helpers for use by NAND controllers.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2753 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 77 insertions, 0 deletions

diff --git a/ecc.h b/ecc.h
new file mode 100644
index 0000000..11e6d01
--- /dev/null
+++ b/ecc.h
@@ -0,0 +1,77 @@
+/*
+ * Calculate Error-correcting Codes. Used by NAND Flash controllers
+ * (not by NAND chips).
+ *
+ * Copyright (c) 2006 Openedhand Ltd.
+ * Written by Andrzej Zaborowski <balrog@zabor.org>
+ *
+ * This code is licensed under the GNU GPL v2.
+ */
+
+struct ecc_state_s {
+    uint8_t cp;		/* Column parity */
+    uint16_t lp[2];	/* Line parity */
+    uint16_t count;
+};
+
+/*
+ * Pre-calculated 256-way 1 byte column parity.  Table borrowed from Linux.
+ */
+static const uint8_t nand_ecc_precalc_table[] = {
+    0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a,
+    0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
+    0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f,
+    0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
+    0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c,
+    0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
+    0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59,
+    0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
+    0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33,
+    0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
+    0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56,
+    0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
+    0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55,
+    0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
+    0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30,
+    0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
+    0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30,
+    0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
+    0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55,
+    0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
+    0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56,
+    0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
+    0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33,
+    0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
+    0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59,
+    0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
+    0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c,
+    0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
+    0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f,
+    0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
+    0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a,
+    0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
+};
+
+/* Update ECC parity count.  */
+static inline uint8_t ecc_digest(struct ecc_state_s *s, uint8_t sample)
+{
+    uint8_t idx = nand_ecc_precalc_table[sample];
+
+    s->cp ^= idx & 0x3f;
+    if (idx & 0x40) {
+        s->lp[0] ^= ~s->count;
+        s->lp[1] ^= s->count;
+    }
+    s->count ++;
+
+    return sample;
+}
+
+/* Reinitialise the counters.  */
+static inline void ecc_reset(struct ecc_state_s *s)
+{
+    s->lp[0] = 0x0000;
+    s->lp[1] = 0x0000;
+    s->cp = 0x00;
+    s->count = 0;
+}