Add primes generator

1 files changed, 74 insertions, 0 deletions

diff --git a/input/primes-generator.asm b/input/primes-generator.asm
new file mode 100644
index 0000000..f772fc3
--- /dev/null
+++ b/input/primes-generator.asm
@@ -0,0 +1,74 @@
+;;;;;;;;
+;;; discovers factors from 0-N through use of the trial division algorithm.
+;;;
+;;; I didn't write a square root function, so this is worse than algorithms
+;;; you'll find online. That may be better. :)
+
+.data
+	N 5000
+	primes 0
+.text
+	addi $5 $2 0x0		; establish frame pointer
+	addi $6 $0 0x0 		; establish return argument
+	jmp MAIN
+
+TRIAL:
+	push $5			;function preamble
+	addi $5 $2 0x0
+	subi $2 $2 0x0
+
+	load $7 +1($5) 		; N (argument)
+	addi $8 $0 0x2 		; the initial divisor
+	addi $6 $0 0x0 		; the return value
+
+	jrl TCOND
+TLOOP:
+	rem $9 $7 $8 		; check if divisible
+	cmp $9 $0
+	beq END
+
+	addi $8 $8 0x1
+TCOND:
+	cmp  $7 $8
+	bgt TLOOP
+
+	addi $6 $0 0x1 		; return 1 (signal parameter is prime)
+END:
+	addi $2 $5 0x0		; function postamble
+	pop $5
+	ret
+
+MAIN:
+	push $5			; function preamble
+	addi $5 $2 0x0
+	subi $2 $2 0x3
+
+	load $7 N($0) 		; N
+	addi $8 $0 0x2 		; number to test
+	addi $9 $0 0x0 		; index to store
+
+GEN:
+	store $9 -1($5) 	; caller-saved registers
+	store $8 -2($5)
+	store $7 -3($5)
+
+	push $8 		; push arg
+	jal TRIAL
+	addi $2 $2 0x1
+
+	load $9 -1($5) 		; restore registers
+	load $8 -2($5)
+	load $7 -3($5)
+
+	cmp $6 $0 		; check if return is 0
+	beq COMPOSITE
+
+	store $8 primes($9) 	; store prime
+	addi $9 $9 0x1
+COMPOSITE:
+	addi $8 $8 0x1
+	cmp  $7 $8
+	bgt GEN
+	nop
+	nop
+	nop