Data commit

Task/Copy-a-string/6502-Assembly/copy-a-string.6502

@@ -0,0 +1,35 @@
+source equ $10            ;$10 was chosen arbitrarily
+source_hi equ source+1    ;the high byte MUST be after the low byte, otherwise this will not work.
+dest equ $12
+dest_hi equ dest+1
+
+LDA #<MyString ;get the low byte of &MyString
+STA source
+LDA #>MyString ;get the high byte
+STA source_hi  ;we just created a "shallow reference" to an existing string.
+               ;As it turns out, this is a necessary step to do a deep copy.
+
+LDA #<RamBuffer
+STA dest
+LDA #>RamBuffer
+STA dest_hi
+
+
+strcpy:
+;assumes that RamBuffer is big enough to hold the source string, and that the memory ranges do not overlap.
+;if you've ever wondered why C's strcpy is considered "unsafe", this is why.
+
+LDY #0
+.again:
+LDA (source),y
+STA (dest),y
+BEQ .done
+INY
+BNE .again   ;exit after 256 bytes copied or the null terminator is reached, whichever occurs first.
+RTS
+
+
+MyString:
+byte "hello",0
+RamBuffer:
+byte 0,0,0,0,0,0