Block device peripheral and SBFS file system implemented.

2026-08-16 14:03:29 -04:00
parent 04dfcd707b
commit eff6902bcf
36 changed files with 3251 additions and 31 deletions
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+; The negative sense branches.
+;
+; A quarter of every conditional branch in the corpus used to be a branch over an
+; unconditional one, because only "branch if zero" existed. Each of those needed a label
+; invented purely to be jumped past, which is a cost in names as much as in bytes.
+;
+; These test the register directly, the way the positive ones do. A branch on this machine
+; never depends on which instruction ran last, except for the two that read the Carry Flag
+; and say so in their names.
+;
+; Each case is checked both ways round, so a branch that always went the same way would
+; be caught rather than looking correct half the time.
+;
+; Correct output is:
+;   QAB C qab c
+;   9876543210
+
+#Include print.asm
+
+#Program
+
+start:
+  ; ---- Each one taken when it should be. ----
+  RSTA
+  INIB 0d1
+  CCF
+  ADD                   ; Q is 1, so not zero.
+  BNQ qTaken
+  BRI wrong
+qTaken:
+  INIA 0d81             ; 'Q'
+  OUTA 0x00
+
+  INIA 0d5
+  BNA aTaken
+  BRI wrong
+aTaken:
+  INIA 0d65             ; 'A'
+  OUTA 0x00
+
+  INIB 0d5
+  BNB bTaken
+  BRI wrong
+bTaken:
+  INIA 0d66             ; 'B'
+  OUTA 0x00
+
+  CCF
+  BNC cTaken
+  BRI wrong
+cTaken:
+  CALL blankSpace
+  INIA 0d67             ; 'C'
+  OUTA 0x00
+  CALL blankSpace
+
+  ; ---- And each one not taken when it should not be. ----
+  RSTA
+  RSTB
+  CCF
+  ADD                   ; Q is zero.
+  BNQ wrong
+  INIA 0d113            ; 'q'
+  OUTA 0x00
+
+  RSTA
+  BNA wrong
+  INIA 0d97             ; 'a'
+  OUTA 0x00
+
+  RSTB
+  BNB wrong
+  INIA 0d98             ; 'b'
+  OUTA 0x00
+
+  ; Set the carry by overflowing, then check BNC does not take it.
+  INIA 0xFF
+  INIB 0x01
+  CCF
+  ADD
+  BNC wrong
+  CALL blankSpace
+  INIA 0d99             ; 'c'
+  OUTA 0x00
+  CALL lineFeed
+
+  ; ---- A countdown, which is what the missing sense was mostly wanted for. ----
+  ; Before these existed this loop needed a label to jump over, and now it does not.
+  INIA 0d10
+  SETD.0 Count
+  STA.0
+countLoop:
+  LDA.0
+  DECA                  ; Ten down to one becomes nine down to zero.
+  INIB 0d48             ; '0'
+  CCF
+  ADD
+  MVQA
+  OUTA 0x00
+  LDA.0
+  DECA
+  STA.0
+  BNA countLoop         ; One instruction where it used to take two and a label.
+  CALL lineFeed
+  HALT
+
+wrong:
+  SETD.0 Wrong
+  CALL printString
+  CALL lineFeed
+  HALT
+
+#Data
+Wrong:
+"a branch went the wrong way"
+Count:
+  0x00