AnachronautandClaude Opus 5
ccf4b384e1
Five .asm files sat at the top of Programs/ beside six directories, with
nothing to say which a new file should join - and hello.asm, which is the
native assembler's first target and named in sixteen places, looked like a
stray.
Programs/
Examples/ what you read to learn: hello, printHello, inputTest,
replCalculator, and Fibonacci, primeSieve and gameOfLife
as sets of their own
Libraries/ included by name, no entry point of their own
Loader/ loader.asm, and the loadable program it reads
CosmOS/ the system, its applications and its assembler
testPrograms/ what 'make test' drives
Loader/ is the one worth explaining. loader.asm is not a demonstration: it
reads a program off a disk, puts the two pieces where the header asks, and
jumps to the entry. CosmOS grew out of it and does the same thing as one of
its commands. It is kept because backward compatibility with the simplest
version of the system is a standing goal, and it was sitting loose next to
the demos as though it were one.
Programs/loadable/ was a directory holding one file called hello.asm - a
third thing of that name, and the name said nothing about why it was there.
It is Loader/loadable.asm now, beside the loader that reads it.
Every reference moved with them: the makefile's program list, twelve
manifest lines, makedisks.sh, native.sh, and four paths across the README
and both manuals. Verified by deleting both build directories and running
the whole suite from nothing.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
68 lines
3.2 KiB
NASM
68 lines
3.2 KiB
NASM
; This is an implementation of The Sieve of Eratosthenes that finds all the primes between 2 and 255.
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#Include print.asm
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#Program
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start:
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; Search the list until we find a prime.
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SETD DataTop
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CCF ; Clear the carry flag. In later cycles, the carry flag will be set at the end of the next loop. We'll want it cleared.
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RSTA
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RSTB
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findPrimeLoop:
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LDB ; Load an element into B.
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BRB foundPrime ; If it's zero, it's a prime.
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INCA ; Increment A, our index.
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INCD ; Increment the Data Pointer.
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BRA end ; If A becomes zero, we've looked through the whole list without finding another prime.
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BRI findPrimeLoop ; Keep searching for the next prime.
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foundPrime:
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; If we've found a prime, we should print it and mark it off the list so we don't print it again.
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CALL printByteDecimal ; A contains our prime, so we can just call the print subroutine.
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CALL blankSpace ; Put a space afterward to keep things easy to read.
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INIB 0x01 ; Set B to 1.
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STB ; Mark this prime off the list.
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markMultiples:
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; Now, we mark each multiple of this prime as nonprime until we reach the end of the list.
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PSHD ; Save the Data Pointer to the stack.
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POPB ; Pop its low byte into B.
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ADD ; Add them together.
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PSHQ ; Store the result back onto the stack.
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POPD ; Pop the modified address into the Data Pointer.
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INIB 0x01 ; Set B to 1.
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STB ; Store B to mark the value as nonprime.
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BRC start ; If the previous add overflowed, the next nonprime is outside the range of our list, so start over with a new prime.
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BRI markMultiples ; Otherwise, loop again to mark the next multiple as nonprime.
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end:
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CALL lineFeed ; Print a linefeed to make it look nice.
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HALT ; The program is done, we found all the primes!
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#Data
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; The table of our prime candidates. It has to begin on a page boundary: marking walks
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; the pointer's low byte and treats the carry out as running off the end of the table,
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; which only finds the right end if the table starts on one.
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#Align 0x100
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DataTop:
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0x01 0x01 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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