#.md

Funny thing ... because SDCC do not generate good code for this uint8_t* address = (uint8_t *)((hiAddress << 8) | loAddress); new version is even worst than old ... but finally asm version is 11% faster

old

new

asm

magnets_final.asm

	.title  "magnets_s"
	.module magnets_s

	.area _CODE
	newRobboY			=	15
	newRobboX			=	14
	robboMagnetDrag		=	13
	DIR_RIGHT			=	0x0
	DIR_LEFT			=	0x2
	DIR_NONE			=	0x8
	TILE_MAGNET_RIGHT	=	0x0c
	TILE_MAGNET_LEFT	=	0x1c
	
	.globl _playSound
	.globl _currentState
	
_checkMagnet::
;uint8_t hiAddress = 0xc0 | (currentState.newRobboY >> 4);
	ld		a,	(#(_currentState + newRobboY))
	ld		b,	a
	swap	a
	and		a,	#0x0f
	or		a,	#0xc0
;!!!!!!!!!!!!! c = hiAddress
	ld		c,	a
;uint8_t lowY = currentState.newRobboY << 4;
	ld		a,	b
	swap	a
	and		a,	#0xf0
;!!!!!!!!!!!! d = lowY
	ld		d,	a
;checked.all  = 0;
;!!!!!!!!!!!! e = checked
	ld		e,	#0x00
;uint8_t x = 1
;!!!!!!!!!!!!! b = x
	ld		b,	#0x01
;do
loopStart$:
;if (!checked.right)
	ld		a,	e
	and		a,	#0x02
	jr		NZ,	checkLeft$
;uint8_t nextX = currentState.newRobboX + x;
	ld		a,	(#(_currentState + newRobboX))
	add		a,	b
;if (nextX <  16)
	bit		4,	a
	jr		NZ,	checkedRight$
;uint16_t address = (nextX | lowY) | (hiAddress << 8);
	or		a,	d
	ld		l,	a
	ld		h,	c
;uint8_t tile = *((uint8_t*)address);
	ld		a,	(hl)
;if (tile == TILE_MAGNET_LEFT)
	cp		a,	#TILE_MAGNET_LEFT
	jr		NZ,	checkIfRightTileNotEmpty$
;currentState.robboMagnetDrag = DIR_RIGHT;
	ld		hl,	#(_currentState + robboMagnetDrag)
	ld		(hl),#DIR_RIGHT
;playSound(magnetSound);
	ld		de,	#_magnetSound
	push	de
	call	_playSound
	pop		hl
;return;
	jr		return$
checkIfRightTileNotEmpty$:
;else if (tile != TILE_EMPTY)
	or		a,	a
	jr		Z,	checkLeft$
checkedRight$:
;checked.right = TRUE;
	set		1,	e
checkLeft$:
;if (!checked.left)
	ld		a,	e
	and		a,	#0x01
	jr		NZ,	loopCheck$
;uint8_t prevX = currentState.newRobboX - x;
	ld		a,	(#(_currentState + newRobboX))
	sub		a,	b
;if (prevX > 0)
	jr		Z,	checkedLeft$
;uint16_t address = (prevX | lowY) | (hiAddress << 8);
	or		a,	d
	ld		l,	a
	ld		h,	c
;uint8_t tile = *((uint8_t*)address);
	ld		a,	(hl)
;if (tile == TILE_MAGNET_RIGHT)
	cp		a,	#TILE_MAGNET_RIGHT
	jr		NZ,	checkIfLeftTileNotEmpty$
;currentState.robboMagnetDrag = DIR_LEFT;
	ld		hl,	#(_currentState + robboMagnetDrag)
	ld		(hl),#DIR_LEFT
;playSound(magnetSound);
	ld		de,	#_magnetSound
	push	de
	call	_playSound
	pop		hl
;return;
	jr		return$
checkIfLeftTileNotEmpty$:
;else if (tile != TILE_EMPTY)
	or		a,	a
	jr		Z,	loopCheck$
checkedLeft$:
;checked.left = TRUE;
	set		0,	e
loopCheck$:
;while (++x < 16 && checked.all != 0b11)
	inc		b
	ld		a,	b
	sub		a,	#0x10
	jr		NC,	magnetNotFound$
	ld		a,	e
	sub		a,	#0x03
	jr		NZ,	loopStart$
magnetNotFound$:
;currentState.robboMagnetDrag = DIR_NONE;
	ld		hl,	#(_currentState + robboMagnetDrag)
	ld		(hl),#DIR_NONE

return$:
	ret

magnets_new.c

#define LEFT	1
#define RIGHT	2

void checkMagnet() 
{
	uint8_t checked = 0;
	uint8_t hiAddress = 0xc0 | (currentState.newRobboY >> 4);
	uint8_t lowY = currentState.newRobboY << 4;
	uint8_t x = 1;
	do
	{
		if (!(checked & RIGHT))
		{
			uint8_t nextX = currentState.newRobboX + x;
			if ((nextX & 0x10) == 0)
			{
				uint8_t loAddress = nextX | lowY;
				uint8_t* address = (uint8_t *)((hiAddress << 8) | loAddress);
				uint8_t tile = *(address);
				if (tile == TILE_MAGNET_LEFT)
				{
					currentState.robboMagnetDrag = DIR_RIGHT;
					playSound(magnetSound);
					return;
				}
				else if (tile != TILE_EMPTY)
					goto checkedRight;
			}
			else
			{
checkedRight:
				checked |= RIGHT;
			}
		}
		if (!(checked & LEFT))
		{
			uint8_t prevX = currentState.newRobboX - x;
			if ((prevX & 0x10) == 0)
			{
				uint8_t loAddress = prevX | lowY;
				uint8_t* address = (uint8_t*)((hiAddress << 8) | loAddress);
				uint8_t tile = *(address);
				if (tile == TILE_MAGNET_RIGHT)
				{
					currentState.robboMagnetDrag = DIR_LEFT;
					playSound(magnetSound);
					return;
				}
				else if (tile != TILE_EMPTY)
					goto checkedLeft;
			}
			else
			{
checkedLeft:
				checked |= LEFT;
			}
		}
	} while (++x < 16 && checked != (LEFT | RIGHT));
	currentState.robboMagnetDrag = DIR_NONE;
}

magnets_old.c

#define LEFT	1
#define RIGHT	2

void checkMagnet() 
{
	uint8_t checked = 0;
	uint8_t* mapY = currentLevel.map + 16 * currentState.newRobboY;
	uint8_t x = 1;
	do
	{
		if (!(checked & RIGHT))
		{
			uint8_t nextX = currentState.newRobboX + x;
			if ((nextX & 0x10) == 0)
			{
				uint8_t tile = *(mapY + nextX);
				if (tile == TILE_MAGNET_LEFT)
				{
					currentState.robboMagnetDrag = DIR_RIGHT;
					playSound(magnetSound);
					return;
				}
				else if (tile != TILE_EMPTY)
					goto checkedRight;
			}
			else
			{
checkedRight:
				checked |= RIGHT;
			}
		}
		if (!(checked & LEFT))
		{
			uint8_t prevX = currentState.newRobboX - x;
			if ((prevX & 0x10) == 0)
			{
				uint8_t tile = *(mapY + prevX);
				if (tile == TILE_MAGNET_RIGHT)
				{
					currentState.robboMagnetDrag = DIR_LEFT;
					playSound(magnetSound);
					return;
				}
				else if (tile != TILE_EMPTY)
					goto checkedLeft;
			}
			else
			{
checkedLeft:
				checked |= LEFT;
			}
		}
	} while (++x < 16 && checked != (LEFT | RIGHT));
	currentState.robboMagnetDrag = DIR_NONE;
}