path: root/firmware/asm
diff options
authorMichael Sevakis <>2013-08-05 22:02:45 -0400
committerMichael Sevakis <>2014-08-30 03:48:23 +0200
commit7d1a47cf13726c95ac46027156cc12dd9da5b855 (patch)
treeeb20d07656806479a8e1fea25887a490ea30d1d8 /firmware/asm
parent95a4c3afcd53a1f8b835dec33de51f9c304de4d9 (diff)
Rewrite filesystem code (WIP)
This patch redoes the filesystem code from the FAT driver up to the clipboard code in onplay.c. Not every aspect of this is finished therefore it is still "WIP". I don't wish to do too much at once (haha!). What is left to do is get dircache back in the sim and find an implementation for the dircache indicies in the tagcache and playlist code or do something else that has the same benefit. Leaving these out for now does not make anything unusable. All the basics are done. Phone app code should probably get vetted (and app path handling just plain rewritten as environment expansions); the SDL app and Android run well. Main things addressed: 1) Thread safety: There is none right now in the trunk code. Most of what currently works is luck when multiple threads are involved or multiple descriptors to the same file are open. 2) POSIX compliance: Many of the functions behave nothing like their counterparts on a host system. This leads to inconsistent code or very different behavior from native to hosted. One huge offender was rename(). Going point by point would fill a book. 3) Actual running RAM usage: Many targets will use less RAM and less stack space (some more RAM because I upped the number of cache buffers for large memory). There's very little memory lying fallow in rarely-used areas (see 'Key core changes' below). Also, all targets may open the same number of directory streams whereas before those with less than 8MB RAM were limited to 8, not 12 implying those targets will save slightly less. 4) Performance: The test_disk plugin shows markedly improved performance, particularly in the area of (uncached) directory scanning, due partly to more optimal directory reading and to a better sector cache algorithm. Uncached times tend to be better while there is a bit of a slowdown in dircache due to it being a bit heavier of an implementation. It's not noticeable by a human as far as I can say. Key core changes: 1) Files and directories share core code and data structures. 2) The filesystem code knows which descriptors refer to same file. This ensures that changes from one stream are appropriately reflected in every open descriptor for that file (fileobj_mgr.c). 3) File and directory cache buffers are borrowed from the main sector cache. This means that when they are not in use by a file, they are not wasted, but used for the cache. Most of the time, only a few of them are needed. It also means that adding more file and directory handles is less expensive. All one must do in ensure a large enough cache to borrow from. 4) Relative path components are supported and the namespace is unified. It does not support full relative paths to an implied current directory; what is does support is use of "." and "..". Adding the former would not be very difficult. The namespace is unified in the sense that volumes may be specified several times along with relative parts, e.g.: "/<0>/foo/../../<1>/bar" :<=> "/<1>/bar". 5) Stack usage is down due to sharing of data, static allocation and less duplication of strings on the stack. This requires more serialization than I would like but since the number of threads is limited to a low number, the tradoff in favor of the stack seems reasonable. 6) Separates and heirarchicalizes (sic) the SIM and APP filesystem code. SIM path and volume handling is just like the target. Some aspects of the APP file code get more straightforward (e.g. no path hashing is needed). Dircache: Deserves its own section. Dircache is new but pays homage to the old. The old one was not compatible and so it, since it got redone, does all the stuff it always should have done such as: 1) It may be update and used at any time during the build process. No longer has one to wait for it to finish building to do basic file management (create, remove, rename, etc.). 2) It does not need to be either fully scanned or completely disabled; it can be incomplete (i.e. overfilled, missing paths), still be of benefit and be correct. 3) Handles mounting and dismounting of individual volumes which means a full rebuild is not needed just because you pop a new SD card in the slot. Now, because it reuses its freed entry data, may rebuild only that volume. 4) Much more fundamental to the file code. When it is built, it is the keeper of the master file list whether enabled or not ("disabled" is just a state of the cache). Its must always to ready to be started and bind all streams opened prior to being enabled. 5) Maintains any short filenames in OEM format which means that it does not need to be rebuilt when changing the default codepage. Miscellaneous Compatibility: 1) Update any other code that would otherwise not work such as the hotswap mounting code in various card drivers. 2) File management: Clipboard needed updating because of the behavioral changes. Still needs a little more work on some finer points. 3) Remove now-obsolete functionality such as the mutex's "no preempt" flag (which was only for the prior FAT driver). 4) struct dirinfo uses time_t rather than raw FAT directory entry time fields. I plan to follow up on genericizing everything there (i.e. no FAT attributes). 5) unicode.c needed some redoing so that the file code does not try try to load codepages during a scan, which is actually a problem with the current code. The default codepage, if any is required, is now kept in RAM separarately (bufalloced) from codepages specified to iso_decode() (which must not be bufalloced because the conversion may be done by playback threads). Brings with it some additional reusable core code: 1) Revised file functions: Reusable code that does things such as safe path concatenation and parsing without buffer limitations or data duplication. Variants that copy or alter the input path may be based off these. To do: 1) Put dircache functionality back in the sim. Treating it internally as a different kind of file system seems the best approach at this time. 2) Restore use of dircache indexes in the playlist and database or something effectively the same. Since the cache doesn't have to be complete in order to be used, not getting a hit on the cache doesn't unambiguously say if the path exists or not. Change-Id: Ia30f3082a136253e3a0eae0784e3091d138915c8 Reviewed-on: Reviewed-by: Michael Sevakis <> Tested: Michael Sevakis <>
Diffstat (limited to 'firmware/asm')
2 files changed, 16 insertions, 16 deletions
diff --git a/firmware/asm/mips/memcpy.S b/firmware/asm/mips/memcpy.S
index 2e7f245c69..edbf5ac5eb 100644
--- a/firmware/asm/mips/memcpy.S
+++ b/firmware/asm/mips/memcpy.S
@@ -63,13 +63,13 @@ memcpy:
SWHI t0, 0(a0)
addu a0, t1
andi t0, a2, 0x1f # 32 or more bytes left?
beq t0, a2, chk1w
subu a3, a2, t0 # Yes
addu a3, a1 # a3 = end address of loop
move a2, t0 # a2 = what will be left after loop
lw t0, 0(a1) # Loop taking 8 words at a time
lw t1, 4(a1)
lw t2, 8(a1)
@@ -90,34 +90,34 @@ lop8w:
bne a1, a3, lop8w
sw t7, -4(a0)
andi t0, a2, 0x3 # 4 or more bytes left?
beq t0, a2, last8
subu a3, a2, t0 # Yes, handle them one word at a time
addu a3, a1 # a3 again end address
move a2, t0
lw t0, 0(a1)
addiu a0, 4
addiu a1, 4
bne a1, a3, lop1w
sw t0, -4(a0)
blez a2, lst8e # Handle last 8 bytes, one at a time
addu a3, a2, a1
lb t0, 0(a1)
addiu a0, 1
addiu a1, 1
bne a1, a3, lst8l
sb t0, -1(a0)
jr ra # Bye, bye
- subu a3, zero, a0 # Src and Dest unaligned
+ subu a3, zero, a0 # Src and Dest unaligned
andi a3, 0x3 # (unoptimized case...)
beq a3, zero, shft1
subu a2, a3 # a2 = bytes left
@@ -126,11 +126,11 @@ shift:
addu a1, a3
SWHI t0, 0(a0)
addu a0, a3
andi t0, a2, 0x3
subu a3, a2, t0
addu a3, a1
LWHI t1, 0(a1) # Limp through, word by word
LWLO t1, 3(a1)
addiu a0, 4
diff --git a/firmware/asm/sh/memcpy.S b/firmware/asm/sh/memcpy.S
index e23a579b05..59c5801ac0 100644
--- a/firmware/asm/sh/memcpy.S
+++ b/firmware/asm/sh/memcpy.S
@@ -60,13 +60,13 @@ ___memcpy_fwd_entry:
cmp/hs r0,r6 /* at least 11 bytes to copy? (ensures 2 aligned longs) */
add r5,r6 /* r6 = source_end */
bf .start_b2 /* no: jump directly to byte loop */
mov #3,r0
neg r5,r3
and r0,r3 /* r3 = (4 - align_offset) % 4 */
tst r3,r3 /* already aligned? */
bt .end_b1 /* yes: skip leading byte loop */
add r5,r3 /* r3 = first source long bound */
/* leading byte loop: copies 0..3 bytes */
@@ -89,7 +89,7 @@ ___memcpy_fwd_entry:
mov r6,r3 /* move end address to r3 */
jmp @r1 /* and jump to it */
add #-7,r3 /* adjust end addr for main loops doing 2 longs/pass */
/** main loops, copying 2 longs per pass to profit from fast page mode **/
/* long aligned destination (fastest) */
@@ -102,11 +102,11 @@ ___memcpy_fwd_entry:
mov.l r0,@-r4 /* store second long */
mov.l r1,@-r4 /* store first long; NOT ALIGNED - no speed loss here! */
bt .loop_do0
add #4,r3 /* readjust end address */
cmp/hi r5,r3 /* one long left? */
bf .start_b2 /* no, jump to trailing byte loop */
mov.l @r5+,r0 /* load last long & increment source addr */
add #4,r4 /* increment dest addr */
bra .start_b2 /* jump to trailing byte loop */