From 2bd748fccd62ff8268d8f7e606f542f491fcb7d6 Mon Sep 17 00:00:00 2001
From: Bradford Lamson-Scribner <brad.lamson@gmail.com>
Date: Sat, 30 May 2020 11:13:35 -0600
Subject: [PATCH] docs: update some funcs with light docs

---
 internal/vm/cpu.go | 4 ++--
 internal/vm/vm.go  | 8 ++++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/internal/vm/cpu.go b/internal/vm/cpu.go
index affdc2e..dd03aed 100644
--- a/internal/vm/cpu.go
+++ b/internal/vm/cpu.go
@@ -68,7 +68,7 @@ const (
 	flagCarry             uint8 = 0B_00000001
 )
 
-// StackBottom represents the bottom address
+// StackBottom represents the start of the stack
 const StackBottom uint16 = 0x0100 // 256
 
 // Mos6502 TODO: docs
@@ -81,7 +81,7 @@ type Mos6502 struct {
 	ps uint8  // register - processor status
 }
 
-// newCPU TODO: docs
+// newCPU initializes and returns a new Mos6502 CPU
 func newCPU() *Mos6502 {
 	return &Mos6502{
 		sp: 0xFF,
diff --git a/internal/vm/vm.go b/internal/vm/vm.go
index 8e8e404..b0fd353 100644
--- a/internal/vm/vm.go
+++ b/internal/vm/vm.go
@@ -36,11 +36,13 @@ func (a *Appleone) step() {
 	}
 }
 
-func (a *Appleone) pushWordToStack(data byte) {
-	a.mem[StackBottom+uint16(a.cpu.sp)] = data
+// pushWordToStack pushes the given word (byte) into memory and sets the new stack pointer
+func (a *Appleone) pushWordToStack(b byte) {
+	a.mem[StackBottom+uint16(a.cpu.sp)] = b
 	a.cpu.sp = uint8((uint16(a.cpu.sp) - 1) & 0xFF)
 }
 
+// pushWordToStack splits the high and low byte of the data passed in, and pushes them to the stack
 func (a *Appleone) pushDWordToStack(data uint16) {
 	h := uint8((data >> 8) & 0xFF)
 	l := uint8(data & 0xFF)
@@ -48,11 +50,13 @@ func (a *Appleone) pushDWordToStack(data uint16) {
 	a.pushWordToStack(l)
 }
 
+// popStackWord sets the new stack pointer and returns the appropriate byte in memory
 func (a *Appleone) popStackWord() uint8 {
 	a.cpu.sp = uint8((uint16(a.cpu.sp) + 1) & 0xFF)
 	return a.mem[StackBottom+uint16(a.cpu.sp)]
 }
 
+// popStackDWord pops two stack words (a double word - uint16) off the stack
 func (a *Appleone) popStackDWord() uint16 {
 	l := a.popStackWord()
 	h := a.popStackWord()