Block device peripheral and SBFS file system implemented.
This commit is contained in:
Anachronaut
@@ -0,0 +1,117 @@
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; The negative sense branches.
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;
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; A quarter of every conditional branch in the corpus used to be a branch over an
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; unconditional one, because only "branch if zero" existed. Each of those needed a label
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; invented purely to be jumped past, which is a cost in names as much as in bytes.
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;
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; These test the register directly, the way the positive ones do. A branch on this machine
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; never depends on which instruction ran last, except for the two that read the Carry Flag
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; and say so in their names.
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;
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; Each case is checked both ways round, so a branch that always went the same way would
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; be caught rather than looking correct half the time.
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;
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; Correct output is:
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; QAB C qab c
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; 9876543210
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#Include print.asm
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#Program
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start:
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; ---- Each one taken when it should be. ----
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RSTA
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INIB 0d1
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CCF
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ADD ; Q is 1, so not zero.
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BNQ qTaken
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BRI wrong
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qTaken:
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INIA 0d81 ; 'Q'
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OUTA 0x00
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INIA 0d5
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BNA aTaken
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BRI wrong
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aTaken:
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INIA 0d65 ; 'A'
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OUTA 0x00
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INIB 0d5
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BNB bTaken
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BRI wrong
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bTaken:
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INIA 0d66 ; 'B'
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OUTA 0x00
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CCF
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BNC cTaken
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BRI wrong
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cTaken:
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CALL blankSpace
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INIA 0d67 ; 'C'
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OUTA 0x00
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CALL blankSpace
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; ---- And each one not taken when it should not be. ----
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RSTA
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RSTB
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CCF
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ADD ; Q is zero.
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BNQ wrong
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INIA 0d113 ; 'q'
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OUTA 0x00
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RSTA
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BNA wrong
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INIA 0d97 ; 'a'
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OUTA 0x00
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RSTB
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BNB wrong
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INIA 0d98 ; 'b'
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OUTA 0x00
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; Set the carry by overflowing, then check BNC does not take it.
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INIA 0xFF
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INIB 0x01
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CCF
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ADD
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BNC wrong
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CALL blankSpace
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INIA 0d99 ; 'c'
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OUTA 0x00
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CALL lineFeed
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; ---- A countdown, which is what the missing sense was mostly wanted for. ----
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; Before these existed this loop needed a label to jump over, and now it does not.
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INIA 0d10
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SETD.0 Count
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STA.0
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countLoop:
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LDA.0
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DECA ; Ten down to one becomes nine down to zero.
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INIB 0d48 ; '0'
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CCF
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ADD
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MVQA
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OUTA 0x00
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LDA.0
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DECA
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STA.0
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BNA countLoop ; One instruction where it used to take two and a label.
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CALL lineFeed
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HALT
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wrong:
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SETD.0 Wrong
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CALL printString
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CALL lineFeed
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HALT
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#Data
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Wrong:
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"a branch went the wrong way"
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Count:
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0x00
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@@ -0,0 +1,42 @@
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; A write protected disk.
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;
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; The bar is in the device, not in the filesystem. A flag in a superblock can be got
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; around by writing blocks directly; this cannot be got around at all. It is the tab on
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; the side of a floppy rather than a note asking politely.
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;
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; A disk is read only if it was attached that way, or if the host will not let its image
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; be written. The machine cannot tell the two apart and does not need to.
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;
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; Status bit 2 says the disk is protected. Unlike the busy and error bits it describes the
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; medium rather than the last operation, so it reads true before anything has been asked
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; of the disk at all.
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;
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; Correct output is:
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; 04 protected, before anything has been attempted
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; 04 a read is allowed and does not disturb the bit
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; 06 a write is barred: protected, and the operation failed
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#Include print.asm
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#Program
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start:
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INA 0x23
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CALL printByteHex
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CALL lineFeed
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RSTA
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OUTA 0x20
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OUTA 0x21 ; Block 0.
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INIA 0x01
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OUTA 0x22 ; Read. Reading a protected disk is ordinary.
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INA 0x23
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CALL printByteHex
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CALL lineFeed
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INIA 0x02
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OUTA 0x22 ; Write. Barred by the device.
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INA 0x23
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CALL printByteHex
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CALL lineFeed
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HALT
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@@ -0,0 +1,143 @@
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; Storage.
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;
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; The disk is a block device and nothing more. It knows numbered blocks of 256 bytes and
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; has never heard of a file, which is deliberate: a filesystem is software this machine
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; will run rather than something the host does on its behalf. A disk that understood
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; filenames would be the emulator doing the work while the machine pretended it had.
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;
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; Its buffer is one block, and like any memory a device brings, it is unreachable until
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; it is registered as a bank and gone through with the controller.
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;
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; Between writing and reading the buffer is scrubbed, so a stale copy of the message
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; sitting in it cannot make a broken read look like a working one.
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;
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; The image is made fresh for every run of the suite, so block 3 is zeroes before this
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; program touches it.
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;
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; Correct output is:
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; 00 the write worked
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; from the disk block 3 came back
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; 02 a block past the end of the image is an error, not a fault
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#Include print.asm
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#Program
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start:
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; The disk's buffer becomes bank 5.
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INIA 0d5
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OUTA 0xE3
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INIA 0x20
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OUTA 0xE2
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INIA 0x03
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OUTA 0xE8
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; Put the message into the buffer and write it to block 3.
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SETD.0 Message
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CALL aimSourceData
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CALL aimDestBuffer
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INIA 0d16
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CALL setLength
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INIA 0x01
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OUTA 0xE8
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CALL selectBlockThree
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INIA 0x02
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OUTA 0x22 ; Write.
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INA 0x23
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CALL printByteHex
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CALL lineFeed
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; Scrub the buffer, so what comes back has to have come off the disk.
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CALL aimDestBuffer
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INIA 0x2D ; '-' as the fill byte.
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OUTA 0xE2
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INIA 0d16
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CALL setLength
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INIA 0x02
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OUTA 0xE8 ; Fill.
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CALL selectBlockThree
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INIA 0x01
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OUTA 0x22 ; Read.
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; Bring the block into Data Memory and print it.
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INIA 0d5
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OUTA 0xE0
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RSTA
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OUTA 0xE1
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OUTA 0xE2
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SETD.0 Landing
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CALL aimDestData
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INIA 0d16
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CALL setLength
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INIA 0x01
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OUTA 0xE8
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SETD.0 Landing
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CALL printString
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CALL lineFeed
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; A block past the end of the image says so in Status rather than stopping the machine.
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; A disk that cannot read a block is an ordinary thing that happens to working programs.
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INIA 0xFF
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OUTA 0x20
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INIA 0xFF
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OUTA 0x21
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INIA 0x01
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OUTA 0x22
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INA 0x23
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CALL printByteHex
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CALL lineFeed
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HALT
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selectBlockThree:
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RSTA
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OUTA 0x20
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INIA 0d3
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OUTA 0x21
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RET
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aimSourceData:
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INIA 0d1
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OUTA 0xE0
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PSHD.0
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POPA
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POPB
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OUTB 0xE1
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OUTA 0xE2
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RET
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aimDestData:
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INIA 0d1
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OUTA 0xE3
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PSHD.0
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POPA
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POPB
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OUTB 0xE4
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OUTA 0xE5
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RET
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aimDestBuffer:
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INIA 0d5
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OUTA 0xE3
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RSTA
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OUTA 0xE4
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OUTA 0xE5
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RET
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setLength:
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PSHA
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RSTA
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OUTA 0xE6
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POPA
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OUTA 0xE7
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RET
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#Data
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Message:
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"from the disk"
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Landing:
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#Reserve 0d20
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@@ -0,0 +1,156 @@
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; Reading the SplitBit Filesystem.
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;
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; The disk this reads was made by SplitDisk, which is the other implementation of the same
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; format. That is what makes this worth running: the library is being checked against
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; something written by different code working from the same written specification, rather
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; than against itself. If the two ever drift, this is where it shows.
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;
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; The cases here are the ones most likely to be wrong. across.txt is longer than a block,
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; so reading it has to carry on from one to the next. Its entry, and the two after it, are
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; in the second directory block, so finding it has to walk past the end of the first.
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; aName22CharactersLong! fills the name field exactly, so there is no zero on the end of
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; it to stop a comparison. empty.txt has no blocks at all.
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;
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; Correct output is:
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; greeting.txt 0000 11 hello from a file
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; across.txt 0002 BC ABCDEFGH...
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; aName22CharactersLong! 0000 16 exactly twenty two!!!!
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; empty.txt 0000 00
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; absent.txt missing
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#Include print.asm
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#Include sbfs.asm
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#Program
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start:
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CALL sbfsMount
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BRQ mounted
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SETD.0 NoMount
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CALL printString
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CALL lineFeed
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HALT
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mounted:
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SETD.0 WantGreeting
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CALL showFile
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SETD.0 WantAcross
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CALL showFile
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SETD.0 WantLongName
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CALL showFile
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SETD.0 WantEmpty
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CALL showFile
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SETD.0 WantAbsent
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CALL showFile
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HALT
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; DP0 names a file. Prints its name, what the directory says about it, and then the file
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; itself. DP3 keeps the name across the calls, because it is the pointer a CALL does not
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; put back.
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showFile:
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PSHD.0
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POPD.3
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CALL printString
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CALL blankSpace
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PSHD.3
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POPD.0
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CALL sbfsFind
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BRQ showFound
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SETD.0 Missing
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CALL printString
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CALL lineFeed
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RET
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showFound:
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SETD.0 SbfsFileBlocks
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LDA.0
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CALL printByteHex
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INCD.0
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LDA.0
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CALL printByteHex
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CALL blankSpace
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SETD.0 SbfsFileTail
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LDA.0
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CALL printByteHex
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CALL blankSpace
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SETD.1 Landing
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CALL sbfsRead
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BRQ showContents
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SETD.0 Failed
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CALL printString
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CALL lineFeed
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RET
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; Writes out exactly as many bytes as the file has, and no more. The length is the block
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; count and the tail side by side: blocks times 256 plus the tail is the same as putting
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; the count in the high byte and the tail in the low one.
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showContents:
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SETD.0 Landing
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SETD.1 SbfsFileBlocks
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DPUP.1 0d01
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LDA.1
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SETD.1 LeftHigh
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STA.1
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SETD.1 SbfsFileTail
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LDA.1
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SETD.1 LeftLow
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STA.1
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showLoop:
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SETD.1 LeftHigh
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LDA.1
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SETD.2 LeftLow
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LDB.2
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OR
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BRQ showEnd ; Nothing left of it.
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|
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LDA.0
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OUTA 0x00
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INCD.0
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SETD.1 LeftLow
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LDA.1
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DECA
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STA.1
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BRC showBorrow ; It went under, so the high byte owes one.
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BRI showLoop
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showBorrow:
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SETD.1 LeftHigh
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LDA.1
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DECA
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STA.1
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BRI showLoop
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showEnd:
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CALL lineFeed
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RET
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#Data
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||||
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WantGreeting:
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"greeting.txt"
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WantAcross:
|
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"across.txt"
|
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WantLongName:
|
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"aName22CharactersLong!"
|
||||
WantEmpty:
|
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"empty.txt"
|
||||
WantAbsent:
|
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"absent.txt"
|
||||
|
||||
NoMount:
|
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"no mount"
|
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Missing:
|
||||
"missing"
|
||||
Failed:
|
||||
"failed"
|
||||
|
||||
LeftHigh:
|
||||
0x00
|
||||
LeftLow:
|
||||
0x00
|
||||
|
||||
Landing:
|
||||
#Reserve 0d1024
|
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@@ -0,0 +1,157 @@
|
||||
; Writing the SplitBit Filesystem.
|
||||
;
|
||||
; A file's size is settled when it is made, because nothing here can grow one afterwards:
|
||||
; files are laid down contiguously, so the block after a file usually belongs to somebody
|
||||
; else. That is the bargain the format makes, and it is why the size comes first.
|
||||
;
|
||||
; The disk already has a file on it, so the second one has to be put somewhere that does
|
||||
; not tread on it. There is no allocation table to consult: with contiguous files the
|
||||
; directory already says which blocks are spoken for, so finding room is a walk through
|
||||
; the entries rather than a lookup.
|
||||
;
|
||||
; What is written is read straight back, through the same directory, so a file that went
|
||||
; down in the wrong place would come back wrong rather than looking plausible.
|
||||
;
|
||||
; Correct output is:
|
||||
; here.txt 0002
|
||||
; first.txt 0003 written by SplitBit itself
|
||||
; second.txt 0004 and a second one after it
|
||||
|
||||
#Include print.asm
|
||||
#Include sbfs.asm
|
||||
|
||||
#Program
|
||||
|
||||
start:
|
||||
CALL sbfsMount
|
||||
BNQ failed
|
||||
|
||||
; What was already there, and where.
|
||||
SETD.0 Existing
|
||||
CALL report
|
||||
BNQ failed
|
||||
|
||||
SETD.0 FirstName
|
||||
SETD.1 FirstText
|
||||
INIA 0d26
|
||||
CALL makeAndWrite
|
||||
BNQ failed
|
||||
|
||||
SETD.0 SecondName
|
||||
SETD.1 SecondText
|
||||
INIA 0d25
|
||||
CALL makeAndWrite
|
||||
BNQ failed
|
||||
|
||||
; And read both of them back off the disk.
|
||||
SETD.0 FirstName
|
||||
CALL report
|
||||
BNQ failed
|
||||
SETD.0 SecondName
|
||||
CALL report
|
||||
BNQ failed
|
||||
HALT
|
||||
|
||||
failed:
|
||||
SETD.0 Failed
|
||||
CALL printString
|
||||
CALL lineFeed
|
||||
HALT
|
||||
|
||||
; DP0 names the file, DP1 is its text, and A is how many bytes of it there are. Nothing
|
||||
; here is longer than a block, so the whole size is the tail.
|
||||
makeAndWrite:
|
||||
; The text goes on the Stack, not into DP3. DP3 is the pointer a call does not put back,
|
||||
; which cuts both ways: it is how a routine hands one out, and it is therefore not a
|
||||
; safe place to leave anything across a call to a routine that might use it. sbfsCreate
|
||||
; does use it.
|
||||
PSHD.1
|
||||
SETD.1 SbfsFileTail
|
||||
STA.1
|
||||
RSTA
|
||||
SETD.1 SbfsFileBlocks
|
||||
STA.1
|
||||
INCD.1
|
||||
STA.1
|
||||
|
||||
CALL sbfsCreate
|
||||
POPD.1 ; Back off the Stack whether it worked or not.
|
||||
BNQ makeFailed
|
||||
CALL sbfsWriteFile
|
||||
RET
|
||||
|
||||
makeFailed:
|
||||
RET
|
||||
|
||||
; Prints a file's name, where it begins, and what is in it.
|
||||
report:
|
||||
PSHD.0
|
||||
POPD.3
|
||||
CALL printString
|
||||
CALL blankSpace
|
||||
PSHD.3
|
||||
POPD.0
|
||||
CALL sbfsFind
|
||||
BNQ reportFailed
|
||||
|
||||
SETD.0 SbfsFileStart
|
||||
LDA.0
|
||||
CALL printByteHex
|
||||
INCD.0
|
||||
LDA.0
|
||||
CALL printByteHex
|
||||
CALL blankSpace
|
||||
|
||||
SETD.1 Landing
|
||||
CALL sbfsRead
|
||||
BNQ reportFailed
|
||||
|
||||
; Everything here fits in one block, so the tail is the whole length.
|
||||
SETD.0 Landing
|
||||
SETD.1 SbfsFileTail
|
||||
LDA.1
|
||||
SETD.1 LeftOver
|
||||
STA.1
|
||||
BRA reportEnd
|
||||
reportLoop:
|
||||
LDA.0
|
||||
OUTA 0x00
|
||||
INCD.0
|
||||
SETD.1 LeftOver
|
||||
LDA.1
|
||||
DECA
|
||||
STA.1
|
||||
BNA reportLoop
|
||||
reportEnd:
|
||||
CALL lineFeed
|
||||
RSTA
|
||||
RSTB
|
||||
CCF
|
||||
ADD
|
||||
RET
|
||||
|
||||
reportFailed:
|
||||
RSTA
|
||||
INIB 0d1
|
||||
CCF
|
||||
ADD
|
||||
RET
|
||||
|
||||
#Data
|
||||
|
||||
Existing:
|
||||
"here.txt"
|
||||
FirstName:
|
||||
"first.txt"
|
||||
SecondName:
|
||||
"second.txt"
|
||||
FirstText:
|
||||
"written by SplitBit itself"
|
||||
SecondText:
|
||||
"and a second one after it"
|
||||
Failed:
|
||||
"failed"
|
||||
LeftOver:
|
||||
0x00
|
||||
Landing:
|
||||
#Reserve 0d512
|
||||
Reference in New Issue
Block a user