SECTION "Control Signals", ROM0

; [in] f: flags set from a previous operation
UpdateFlags:
  ld hl, flags_temp

.check_z:
  jr z, .set_z
  res FLAG_Z, [hl]

.check_c:
  jr c, .set_c
  res FLAG_C, [hl]
  jr .exit

.set_z:
  set FLAG_Z, [hl]
  jr .check_c

.set_c:
  set FLAG_C, [hl]

.exit:
  ret


ctrl_ht:
  ld a, [ctrl]
  ld b, a
  bit CTRL_HT, b
  jr z, .exit

  xor a
  ld [running], a

.exit:
  ret

ctrl_ro:
  ld a, [ctrl]
  ld b, a
  bit CTRL_RO, b
  jr z, .exit

  ; get memory offset based on MAR
  ld hl, ram
  ld a, [mar]
  add l
  ld l, a

  ld a, [hl]
  ld [bus], a

.exit:
  ret

ctrl_io:
  ld a, [ctrl]
  ld b, a
  bit CTRL_IO, b
  jr z, .exit

  ld a, [ir]
  and $0f
  ld [bus], a

.exit:
  ret

ctrl_ao:
  ld a, [ctrl]
  ld b, a
  bit CTRL_AO, b
  jr z, .exit

  ld a, [a_reg]
  ld [bus], a

.exit:
  ret

ctrl_eo:
  ld a, [ctrl+1]
  ld b, a
  bit CTRL_EO, b
  jp z, .exit

  ld a, [alu]
  ld [bus], a

.exit:
  ret

ctrl_co:
  ld a, [ctrl+1]
  ld b, a
  bit CTRL_CO, b
  jp z, .exit

  ld a, [pc]
  ld [bus], a

.exit:
  ret

ctrl_mi:
  ld a, [ctrl]
  ld b, a
  bit CTRL_MI, b
  jp z, .exit

  ld a, [bus]
  ld [mar], a

.exit:
  ret

ctrl_ri:
  ld a, [ctrl]
  ld b, a
  bit CTRL_RI, b
  jp z, .exit

  ; get memory offset based on MAR
  ld hl, ram
  ld a, [mar]
  add l
  ld l, a

  ld a, [bus]
  ld [hl], a

.exit:
  ret

ctrl_ii:
  ld a, [ctrl]
  ld b, a
  bit CTRL_II, b
  jp z, .exit

  ld a, [bus]
  ld [ir], a

.exit:
  ret

ctrl_ai:
  ld a, [ctrl]
  ld b, a
  bit CTRL_AI, b
  jp z, .exit

  ld a, [bus]
  ld [a_reg], a
  ; alu value reflects any change to A or B
  ld d, a
  ld a, [b_reg]
  add d
  ld [alu], a

  call UpdateFlags

.exit:
  ret

ctrl_su:
  ld a, [ctrl+1]
  ld b, a
  bit CTRL_SU, b
  jp z, .exit

  ld a, [b_reg]
  cpl
  inc a
  ld [b_reg], a
  ; alu value reflects any change to A or B
  ld d, a
  ld a, [a_reg]
  add d
  ld [alu], a

  call UpdateFlags

.exit:
  ret

ctrl_bi:
  ld a, [ctrl+1]
  ld b, a
  bit CTRL_BI, b
  jp z, .exit

  ld a, [bus]
  ld [b_reg], a
  ; alu value reflects any change to A or B
  ld d, a
  ld a, [a_reg]
  add d
  ld [alu], a

  call UpdateFlags

.exit:
  ret

ctrl_oi:
  ld a, [ctrl+1]
  ld b, a
  bit CTRL_OI, b
  jp z, .exit

  ld a, [bus]
  ld [out_reg], a

.exit:
  ret

ctrl_ce:
  ld a, [ctrl+1]
  ld b, a
  bit CTRL_CE, b
  jp z, .exit

  ld a, [pc]
  inc a
  ld [pc], a

.exit:
  ret

ctrl_jp:
  ld a, [ctrl+1]
  ld b, a
  bit CTRL_JP, b
  jp z, .exit

  ld a, [bus]
  ld [pc], a

.exit:
  ret

ctrl_fi:
  ld a, [ctrl+1]
  ld b, a
  bit CTRL_FI, b
  jp z, .exit

  ld a, [flags_temp]
  ld [flags], a

.exit:
  ret