working

projects/snow/.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+	"cSpell.words": [
+		"estorm"
+	]
+}

projects/snow/main.s

@@ -49,6 +49,11 @@ main:   stp         x29, x30, [sp, -16]!
 10:     bl          Erase
         bl          StepAll
         bl          RenderAll
+		mov			w0, 1
+		mov			w1, 1
+		bl			Move
+		ldr			x0, =nl
+		bl			printf
         bl          Delay
         b           10b
 
@@ -82,19 +87,89 @@ Erase:  stp         x20, x30, [sp, -16]!
         ldp         x20, x30, [sp], 16
         ret
 
+/*	Address of flake to render comes to us in x0.
+*/
 RenderOne:
+		str			x30, [sp, -16]!
+		ldr			w1, [x0]
+		ldr			w2, [x0, 4]
+		
+		// Ensure 1 <= w1 <= MAX_LINE
+		mov			w3, 1
+		mov			w4, MAX_LINE
+		mov			w5, MAX_COLUMN
+		cmp			w3, w1
+		bgt			99f
+		cmp			w4, w1
+		blt 		99f
+
+		// Ensure 1 <= w2 <= MAX_COLUMN
+		cmp			w3, w2
+		bgt			99f
+		cmp			w5, w2
+		blt 		99f
+
+		ldr			x0, =move_str
+		bl			printf
+		ldr			x0, =char_str
+		bl			printf
+99:		ldr			x30, [sp], 16
         ret
 
+/*	Iterate through the storm rendering each particle
+*/
 RenderAll:
+		stp			x20, x30, [sp, -16]!
+		mov			x20, storm
+1:		mov			x0, x20
+		bl			RenderOne
+		add			x20, x20, Flake.size
+		cmp			estorm, x20
+		bgt			1b
+
+		ldp			x20, x30, [sp], 16
         ret
 
 Delay:
+		str			x30, [sp, -16]!
+		mov			x0, 1
+		lsl 		x0, x0, 17
+		bl			usleep
+		ldr			x30, [sp], 16
         ret
 
+/*	Address of flake to step arrives in x0.
+*/
 StepOne:
+		stp			x20, x30, [sp, -16]!
+		mov			x20, x0
+		ldr			w1, [x0]
+		add			w1, w1, 1
+		str			w1, [x0]
+		mov			w2, MAX_LINE
+		cmp			w2, w1
+		bge 		1f
+		bl			ResetFlake
+1:		bl			rand
+		mov			w1, 3
+		bl			mod
+		sub 		x0, x0, 1
+		ldr			w1, [x20, 4]
+		add 		w0, w0, w1
+		str			w0, [x20, 4]
+		ldp			x20, x30, [sp], 16
         ret
 
 StepAll:
+		stp			x20, x30, [sp, -16]!
+		mov			x20, storm
+1:		mov			x0, x20
+		bl			StepOne
+		add			x20, x20, Flake.size
+		cmp			estorm, x20
+		bgt			1b
+
+		ldp			x20, x30, [sp], 16
         ret
 
 InitializeStorm:
@@ -122,17 +197,17 @@ ResetFlake:
         bl          rand
         mov         x1, MAX_COLUMN
         bl          mod
-        add         w1, w1, 1
-        str         w1, [x20, 4]
+        add         w0, w0, 1
+        str         w0, [x20, 4]
 
         // Initialize Line --- -(1 <= random value <= 48)
 
         bl          rand
         mov         x1, MAX_LINE_X2
         bl          mod
-        add         w1, w1, 1
-        neg         w1, w1
-        str         w1, [x20]
+        add         w0, w0, 1
+        neg         w0, w0
+        str         w0, [x20]
 
         ldp         x20, x30, [sp], 16
         ret
@@ -156,11 +231,12 @@ mod:	sdiv 	x2, x0, x1         // x2 gets a // b
         msub	x0, x2, x1, x0     // x0 gets a - a // b * b	
         ret
 
-
             .data
 bad_malloc: .asciz      "Allocation of flakes has failed"
 move_str:   .asciz      "\033[%d;%dH"
 erase_str:  .asciz      "\033[2J"
+char_str:	.asciz		"*"
+nl:			.asciz		"\n"
 
             .section    Flake
             .struct     0