Diffstat (limited to 'Documentation/mtd/nand_ecc.txt')
1 files changed, 6 insertions, 6 deletions
diff --git a/Documentation/mtd/nand_ecc.txt b/Documentation/mtd/nand_ecc.txt
index bdf93b7f0f2..274821b35a7 100644
@@ -50,7 +50,7 @@ byte 255: bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 rp1 rp3 rp5 ... rp15
cp5 cp5 cp5 cp5 cp4 cp4 cp4 cp4
This figure represents a sector of 256 bytes.
-cp is my abbreviaton for column parity, rp for row parity.
+cp is my abbreviation for column parity, rp for row parity.
Let's start to explain column parity.
cp0 is the parity that belongs to all bit0, bit2, bit4, bit6.
@@ -560,7 +560,7 @@ Measuring this code again showed big gain. When executing the original
linux code 1 million times, this took about 1 second on my system.
(using time to measure the performance). After this iteration I was back
to 0.075 sec. Actually I had to decide to start measuring over 10
-million interations in order not to loose too much accuracy. This one
+million iterations in order not to lose too much accuracy. This one
definitely seemed to be the jackpot!
There is a little bit more room for improvement though. There are three
@@ -571,8 +571,8 @@ loop; This eliminates 3 statements per loop. Of course after the loop we
need to correct by adding:
rp4 ^= rp4_6;
rp6 ^= rp4_6
-Furthermore there are 4 sequential assingments to rp8. This can be
-encoded slightly more efficient by saving tmppar before those 4 lines
+Furthermore there are 4 sequential assignments to rp8. This can be
+encoded slightly more efficiently by saving tmppar before those 4 lines
and later do rp8 = rp8 ^ tmppar ^ notrp8;
(where notrp8 is the value of rp8 before those 4 lines).
Again a use of the commutative property of xor.
@@ -622,7 +622,7 @@ Not a big change, but every penny counts :-)
-Acutally this made things worse. Not very much, but I don't want to move
+Actually this made things worse. Not very much, but I don't want to move
into the wrong direction. Maybe something to investigate later. Could
have to do with caching again.
@@ -642,7 +642,7 @@ Analysis 8
This makes things worse. Let's stick with attempt 6 and continue from there.
Although it seems that the code within the loop cannot be optimised
further there is still room to optimize the generation of the ecc codes.
-We can simply calcualate the total parity. If this is 0 then rp4 = rp5
+We can simply calculate the total parity. If this is 0 then rp4 = rp5
etc. If the parity is 1, then rp4 = !rp5;
But if rp4 = rp5 we do not need rp5 etc. We can just write the even bits
in the result byte and then do something like