From 1ec19679b3db209429b0897f6ccda6d09d018a70 Mon Sep 17 00:00:00 2001
From: mrb0nk500 <b0nk@b0nk.xyz>
Date: Sat, 8 Aug 2020 10:28:36 -0400
Subject: Did a ton of stuff.

- Changed the file structure of the SuB Suite, so that
  all variable declarations, symbols, and constants
  are in a single file.

- Moved the C library functionss into a separate
  file, and made them use stack frames.

- Added support for using the emulator's assembler for
  realtime debugging, to enter it, get in to stepping
  mode by pressing Ctrl+s, press any other key, then
  press F1,
  The reason for having to press some other key before
  pressing F1 is because it only allows entering the
  assembler when the keyboard is not ready.

- Added the ".res" directive to the emulator's
  assembler, the ".res" directive tells the assembler
  to reserve however many bytes specified by the
  operand.

- Fixed some bugs in the emulator's assembler.
---
 test/popcnt.s | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 test/popcnt.s

(limited to 'test/popcnt.s')

diff --git a/test/popcnt.s b/test/popcnt.s
new file mode 100644
index 0000000..7682653
--- /dev/null
+++ b/test/popcnt.s
@@ -0,0 +1,44 @@
+; Calculate population count/hamming weight.
+
+.org $1000
+
+popcnt:
+	ldb #0		; Reset bit count.
+	pha.q		; Create a temporary variable.
+	cmp #0		; Set the status flags.
+@loop:
+	beq @end	; There are no more one bits left, so we're done.
+	dec.q sp+1	; Decrement the temp variable.
+	dec.q sp+1	; Decrement the temp variable.
+	inb		; Increment the bit count.
+	and.q sp+1	; AND value with value-1.
+	sta.q sp+1	; Place it back in the temp variable.
+	bra @loop	; Keep looping.
+@end:
+	pla.q		; Pull/Pop the temp variable off the stack.
+	tba		; Return the bit count.
+	rts		; End of popcnt.
+
+
+reset:
+	cps		; Boilerplate reset code.
+	ldx.w #$FFFF	;
+	txs		;
+	and #0		; Reset A.
+	tab		; Reset B.
+	tax		; Reset X.
+	tay		; Reset Y.
+main:
+	pha.q		; Save A.
+	jsr popcnt	; Get population count.
+	tay		; Save it in Y.
+	pla.q		; Get A back.
+	inc		; Increment A by one.
+	bra main	; Keep looping.
+
+
+.org $FFC0
+.qword reset
+
+a
+d
-- 
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