New SplitBit programs.

2026-08-13 23:42:55 -04:00
parent c2440ae5fa
commit 94b3a7af28
15 changed files with 1155 additions and 0 deletions
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+; A segmented Sieve of Eratosthenes for the complete 16-bit address range.
+;
+; The sieve uses a 256-byte sliding window. Each entry in PrimeStates contains:
+;   prime, high byte of next multiple, low byte of next multiple
+;
+; Once a prime becomes active at p*p, adding an 8-bit prime to offsets in a
+; 256-byte window must wrap exactly once before the next window. The wrapped
+; low byte becomes that prime's starting offset in the following window.
+;
+; Output is hexadecimal (0002 through FFFD), separated by spaces.
+
+#Include Libraries/print.asm
+
+#Program
+
+start:
+  RSTA
+  SETD Page
+  STA
+
+nextPage:
+  ; Clear all 256 flags. A wrapping to zero terminates the loop.
+  SETD Segment
+  RSTA
+  RSTB
+clearSegment:
+  STB
+  INCD
+  INCA
+  BRA segmentCleared
+  BRI clearSegment
+
+segmentCleared:
+  ; Zero and one are not prime.
+  SETD Page
+  LDA
+  BRA excludeZeroAndOne
+  BRI markSegment
+excludeZeroAndOne:
+  SETD Segment
+  INIA 0x01
+  STA
+  INCD
+  STA
+
+markSegment:
+  ; Process the 54 primes not greater than sqrt(0xFFFF).
+  SETD PrimeStates
+  INIA 0d54
+primeLoop:
+  CALL processPrime
+  DPUP 0d03
+  DECA
+  BRA scanSegment
+  BRI primeLoop
+
+scanSegment:
+  ; A is the low byte of the candidate and wraps after 0xFF.
+  SETD Segment
+  RSTA
+scanLoop:
+  LDB
+  BRB emitPrime
+scanNext:
+  INCD
+  INCA
+  BRA advancePage
+  BRI scanLoop
+
+emitPrime:
+  CALL printCandidateHex
+  BRI scanNext
+
+advancePage:
+  SETD Page
+  LDA
+  INCA
+  STA
+  BRA finished
+  BRI nextPage
+
+finished:
+  CALL lineFeed
+  HALT
+
+; DP points at a PrimeStates entry on entry and is preserved by CALL.
+processPrime:
+  PSHD
+  INCD
+  LDA
+  SETD Page
+  LDB
+  XOR
+  BRQ primeIsActive
+  POPD
+  RET
+
+primeIsActive:
+  ; Recover and retain the state-entry pointer for the final update.
+  POPD
+  PSHD
+
+  ; Load the prime into B and its current offset into A.
+  LDA
+  PSHA
+  DPUP 0d02
+  LDA
+  POPB
+
+  ; Form Segment + offset. Segment is page-aligned in Data Memory.
+  SETD Segment
+  PSHB
+  PSHD
+  POPB
+  CCF
+  ADD
+  PSHQ
+  POPD
+  POPB
+
+markPrimeLoop:
+  INIA 0x01
+  STA
+
+  ; Add the prime to the low byte of DP using the stack as a 16-bit
+  ; address adapter. Carry means that the next multiple is in the next page.
+  PSHD
+  POPA
+  CCF
+  ADD
+  PSHQ
+  POPD
+  BRC primeFinished
+  BRI markPrimeLoop
+
+primeFinished:
+  ; Q is the wrapped offset for the next page.
+  POPD
+  INCD
+  LDA
+  INCA
+  STA
+  INCD
+  STQ
+  RET
+
+; A contains the candidate's low byte. Page contains its high byte.
+printCandidateHex:
+  PSHA
+  SETD Page
+  LDA
+  CALL printByteHex
+  POPA
+  CALL printByteHex
+  CALL blankSpace
+  RET
+
+#Data
+
+; print.asm deliberately pads its data to one page, so this begins at 0x0100.
+Segment:
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+
+Page:
+  0x00
+
+PrimeStates:
+  0x02 0x00 0x04
+  0x03 0x00 0x09
+  0x05 0x00 0x19
+  0x07 0x00 0x31
+  0x0B 0x00 0x79
+  0x0D 0x00 0xA9
+  0x11 0x01 0x21
+  0x13 0x01 0x69
+  0x17 0x02 0x11
+  0x1D 0x03 0x49
+  0x1F 0x03 0xC1
+  0x25 0x05 0x59
+  0x29 0x06 0x91
+  0x2B 0x07 0x39
+  0x2F 0x08 0xA1
+  0x35 0x0A 0xF9
+  0x3B 0x0D 0x99
+  0x3D 0x0E 0x89
+  0x43 0x11 0x89
+  0x47 0x13 0xB1
+  0x49 0x14 0xD1
+  0x4F 0x18 0x61
+  0x53 0x1A 0xE9
+  0x59 0x1E 0xF1
+  0x61 0x24 0xC1
+  0x65 0x27 0xD9
+  0x67 0x29 0x71
+  0x6B 0x2C 0xB9
+  0x6D 0x2E 0x69
+  0x71 0x31 0xE1
+  0x7F 0x3F 0x01
+  0x83 0x43 0x09
+  0x89 0x49 0x51
+  0x8B 0x4B 0x79
+  0x95 0x56 0xB9
+  0x97 0x59 0x11
+  0x9D 0x60 0x49
+  0xA3 0x67 0xC9
+  0xA7 0x6C 0xF1
+  0xAD 0x74 0xE9
+  0xB3 0x7D 0x29
+  0xB5 0x7F 0xF9
+  0xBF 0x8E 0x81
+  0xC1 0x91 0x81
+  0xC5 0x97 0x99
+  0xC7 0x9A 0xB1
+  0xD3 0xAD 0xE9
+  0xDF 0xC2 0x41
+  0xE3 0xC9 0x49
+  0xE5 0xCC 0xD9
+  0xE9 0xD4 0x11
+  0xEF 0xDF 0x21
+  0xF1 0xE2 0xE1
+  0xFB 0xF6 0x19