Data commit

Task/Generic-swap/Z80-Assembly/generic-swap-1.z80

@@ -0,0 +1,4 @@
+push ix
+push iy
+pop ix   ;the value that was once in IY is now in IX
+pop iy   ;the value that was once in IX is now in IY

Task/Generic-swap/Z80-Assembly/generic-swap-2.z80

@@ -0,0 +1,8 @@
+;8-bit swap using the stack.
+
+ld a,(&C000)
+push af
+   ld a,(&D000)
+   ld (&C000),a   ;store the byte at &D000 into &C000
+pop af            ;now a = the byte at &C000
+ld (&D000),a      ;now the byte at &D000 equals the byte that was originally at &C000

Task/Generic-swap/Z80-Assembly/generic-swap-3.z80

@@ -0,0 +1,5 @@
+;16-bit swap:
+ld hl,(&C000)     ;load the byte at &C000 into L and the byte at &C001 into H.
+ld de,(&D000)     ;load the byte at &D000 into E and the byte at &D001 into D.
+ld (&D000),hl     ;store the contents of L into &D000 and H into &D001.
+ld (&C000),de     ;store the contents of E into &C000 and D into &C001.

Task/Generic-swap/Z80-Assembly/generic-swap-4.z80

@@ -0,0 +1,4 @@
+push hl
+ld h,d
+ld L,e  ;store de into HL. This is much faster than "push de pop hl."
+pop de ;put old HL into DE

Task/Generic-swap/Z80-Assembly/generic-swap-5.z80

@@ -0,0 +1,20 @@
+ld hl,&C000
+push bc
+ldi a,(hl)  ;equivalent of "ld a,(hl) inc hl" but is faster than the two separately. Some assemblers call this "ld a,(hl+)"
+ld c,a
+ld a,(hl)   ;we don't need to increment hl this time. There's no wasted time or bytecode if we did however.
+ld b,a      ;on Zilog Z80 we would have just done "LD BC,(&C000)" but Game Boy can't do that.
+
+; now we do the swap.
+ld hl,&D000
+
+ld a,(hl)        ;get the byte at &D000
+ld (&C000),a     ;store it into &C000
+ld (hl),c        ;store the old byte at &C000 into &D000
+
+inc hl           ;inc HL to &D001
+
+ld a,(hl)        ;get the byte at &D001
+ld (&C001),a     ;store it at &C001
+ld (hl),b        ;store the old byte at &C001 into &D001
+pop bc