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memcpy: ; src = DE, dest = HL, n = BC
memcpy.loop:
LD A, (DE)
LD (HL+), A
INC DE
DEC BC
XOR A
CP B
JR NZ =memcpy.loop
CP C
JR NZ =memcpy.loop
RET
bzero: ; dest = HL, n = BC
LD A, $00
bzero.loop:
LD (HL+), A
INC DE
DEC BC
CP B
JR NZ =bzero.loop
CP C
JR NZ =bzero.loop
RET
Print_8bit: ; Number in A, Memory Tilemap position in HL
PUSH AF
PUSH BC
LD C, A
SWAP A ; We start by the highest nibble
AND $0f
OR $10
LD (HL+), A
LD A, C
AND $0f ; Then the lowest
OR $10
LD (HL+), A
POP BC
POP AF
RET
MUL: ; B x C => EA
XOR A
LD E, $00
BIT 7, B
JR Z, =MUL.bit7
ADD C
MUL.bit7:
SLA A
RL E
BIT 6, B
JR Z, =MUL.bit6
ADD C
MUL.bit6:
SLA A
RL E
BIT 5, B
JR Z, =MUL.bit5
ADD C
MUL.bit5:
SLA A
RL E
BIT 4, B
JR Z, =MUL.bit4
ADD C
MUL.bit4:
SLA A
RL E
BIT 3, B
JR Z, =MUL.bit3
ADD C
MUL.bit3:
SLA A
RL E
BIT 2, B
JR Z, =MUL.bit2
ADD C
MUL.bit2:
SLA A
RL E
BIT 1, B
JR Z, =MUL.bit1
ADD C
MUL.bit1:
SLA A
RL E
BIT 0, B
JR Z, =MUL.bit0
ADD C
MUL.bit0:
RET
VBlank_Wait:
PUSH AF
LD A, $reg_lcd_controller
BIT 7, A
JR Z, =VBlank_Wait.End
VBlank_Wait.loop:
LD A, $reg_lcd_status
AND $03
CP $01
JR NZ, =VBlank_Wait.loop
VBlank_Wait.End:
POP AF
RET
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