# Flags test

# This is a visual adaptation of the math tests I wrote for Silicon8
# (https://github.com/Timendus/silicon8/tree/main/tests)

:include "../utils/helpers.8o"
:include "../utils/text-rendering.8o"

:alias 15_in_a_register v1
:alias 100_in_a_register v1

:macro opcode-digit OPC {
  vD := OPC
  flags-draw-opcode-digit
}

: flags-draw-opcode-digit
  i := im0
  vE := vD
  vE <<= vE
  vE <<= vE
  i += vE
  sprite x y 4
  x += 5
  return

:macro expect-v0 V0VAL {
  v2 := v0
  vC := V0VAL
  flags-draw-result
}

:macro expect-v2-vf-v3 V2VAL VFVAL V3VAL {
  vE := vF
  vC := V2VAL
  flags-draw-result
  v2 := vE
  vC := VFVAL
  flags-draw-result
  v2 := v3
  vC := V3VAL
  flags-draw-result  
}

:macro expect-v2-vf-v3-v4 V2VAL VFVAL V3VAL V4VAL {
  vE := vF
  vC := V2VAL
  flags-draw-result
  v2 := vE
  vC := VFVAL
  flags-draw-result
  v2 := v3
  vC := V3VAL
  flags-draw-result
  v2 := v4  
  vC := V4VAL
  flags-draw-result
}

: flags-draw-result
  i := flag-err
  if v2 == vC then i := flag-ok
  y += 1
  sprite x y 3
  x += 4
  y -= 1
  return

: main
  clear
  x := 50
  y := 27
  i := version-0-0
  sprite x y 4
  x := 58
  i := version-1-0
  sprite x y 4

  ## Without complications

  text 0 0 flags-no-carry
  x := 22
  y := 0
  15_in_a_register := 15

  # OR
  opcode-digit 1 # 0x81
  v3 := 15
  vF := 20
  v3 |= vF # 31 (0x1F)
  vF := 0 # vF will not be reset if that quirk is not active
  v2 := 50
  v2 |= 15_in_a_register # 63 (0x3F)
  expect-v2-vf-v3 63 0 31
  x += 5

  # AND
  opcode-digit 2 # 0x82
  v3 := 15
  vF := 20
  v3 &= vF # 4 (0x04)
  vF := 0 # vF will not be reset if that quirk is not active
  v2 := 50
  v2 &= 15_in_a_register # 2 (0x02)
  expect-v2-vf-v3 2 0 4
  
  y += 5
  x := 0

  # XOR
  opcode-digit 0x3 # 0x83
  v3 := 15
  vF := 20
  v3 ^= vF # 27 (0x1B)
  vF := 0 # vF will not be reset if that quirk is not active
  v2 := 50
  v2 ^= 15_in_a_register # 61 (0x3D)
  expect-v2-vf-v3 61 0 27
  x += 5

  # Addition (no overflow)
  opcode-digit 0x4 # 0x84
  vF := 20
  vF += 15_in_a_register # 35 (0x23), but should be overwritten by flag, so 0
  v4 := vF
  v3 := 15
  vF := 20
  v3 += vF # 35 (0x23)
  vF := 0xAA
  v2 := 50
  v2 += 15_in_a_register # 65 (0x41)
  expect-v2-vf-v3-v4 65 0 35 0
  x += 1

  # Subtraction in one direction (no carry)
  opcode-digit 0x5 # 0x85
  # Edge cases:
  # Check that vF -= vX results in no carry
  vF := 20
  vF -= 15_in_a_register # 5 (0x05), but should be overwritten by flag, so 1
  v4 := vF
  # Check that vX -= vF results in the correct result and no carry
  v3 := 20
  vF := 15 
  v3 -= vF # 5 (0x05)
  # Check that N - N (for the same N) does not result in carry
  v5 := 10
  vF := 10
  v5 -= vF
  v5 := vF
  # Base case: check that subtracting two regular registers results in the
  # correct value and no carry set, and that the carry register actually gets
  # overwritten.
  vF := 0xAA
  v2 := 50
  v2 -= 15_in_a_register # 35 (0x23)
  # Check all our assertions
  if v5 != 1 then vF := 2
  expect-v2-vf-v3-v4 35 1 5 1

  y += 5
  x := 0

  # Shift right (no LSB)
  opcode-digit 0x6 # 0x86
  vF := 60
  vF >>= vF # 30 (0x1E), but should be overwritten by flag, so 0
  v3 := vF
  vF := 0xAA
  v2 := 60
  v2 >>= v2 # 30 (0x1E)
  expect-v2-vf-v3 30 0 0
  x += 5

  # Subtraction in the other direction (no carry)
  opcode-digit 0x7 # 0x87
  # Edge cases:
  # Check that vF =- vX results in no carry
  vF := 10
  vF =- 15_in_a_register # 5 (0x5), but should be overwritten by flag, so 1
  v4 := vF
  # Check that vX =- vF results in the correct result and no carry
  v3 := 15
  vF := 20
  v3 =- vF # 5 (0x05)
  # Check that N - N (for the same N) does not result in carry
  v5 := 10
  vF := 10
  v5 =- vF
  v5 := vF
  # Base case: check that subtracting two regular registers results in the
  # correct value and no carry set, and taht the carry register actually gets
  # overwritten.
  vF := 0xAA
  v2 := 15
  v1 := 50
  v2 =- v1 # 35 (0x23)
  # Check all our assertions
  if v5 != 1 then vF := 2
  expect-v2-vf-v3-v4 35 1 5 1
  x += 1

  # Shift left (no MSB)
  opcode-digit 0xE # 0x8E
  vF := 50
  vF <<= vF # 100 (0x64), but should be overwritten by flag, so 0
  v3 := vF
  vF := 0xAA
  v2 := 50
  v2 <<= v2 # 100 (0x64)
  expect-v2-vf-v3 100 0 0

  # With complications

  text 0 16 flags-carry
  x := 22
  y := 16
  100_in_a_register := 100

  # Addition (with overflow)
  opcode-digit 0x4 # 0x84
  vF := 200
  vF += 100_in_a_register # 300 (0x2C), but should be overwritten by flag, so 1
  v4 := vF
  v3 := 100
  vF := 200
  v3 += vF # 300 (0x2C)
  vF := 0xAA
  v2 := 200
  v2 += 100_in_a_register # 300, but overflows so 44 (0x2C)
  expect-v2-vf-v3-v4 44 1 44 1
  x += 1

  # Subtraction in one direction (with carry)
  opcode-digit 0x5 # 0x85
  vF := 95
  vF -= 100_in_a_register # -5 = 251 (0xFB), but should be overwritten by flag, so 0
  v4 := vF
  v3 := 95
  vF := 100
  v3 -= vF # -5 = 251 (0xFB)
  vF := 0xAA
  v2 := 95
  v2 -= 100_in_a_register # -5 = 251 (0xFB)
  expect-v2-vf-v3-v4 -5 0 -5 0

  y += 5
  x := 0

  # Shift right (with LSB)
  opcode-digit 0x6 # 0x86
  vF := 61
  vF >>= vF # 30 (0x1E), but should be overwritten by flag, so 1
  v3 := vF
  vF := 0xAA
  v2 := 61
  v2 >>= v2 # 30 (0x1E)
  expect-v2-vf-v3 30 1 1
  x += 5

  # Subtraction in the other direction (with carry)
  opcode-digit 0x7 # 0x87
  vF := 105
  vF =- 100_in_a_register # -5 = 251 (0xFB), but should be overwritten by flag, so 0
  v4 := vF
  v3 := 105
  vF := 100
  v3 =- vF # -5 = 251 (0xFB)
  vF := 0xAA
  v2 := 105
  v2 =- 100_in_a_register # -5 = 251 (0xFB)
  expect-v2-vf-v3-v4 -5 0 -5 0
  x += 1
  
  # Shift left (with MSB)
  opcode-digit 0xE # 0x8E
  vF := 188
  vF <<= vF # 376 (0x178), but should be overwritten by flag, so 1
  v3 := vF
  vF := 0xAA
  v2 := 188
  v2 <<= v2 # 376 (0x178), but overflows so 120 (0x78)
  expect-v2-vf-v3 120 1 1

  # Addition to i

  text 0 27 flags-other
  x := 22
  y := 27

  opcode-digit 0xF # This block
  x -= 1           # draws
  opcode-digit 0xE # opcode 0xFE

  i := scratchpad
  v1 := 16
  i += v1
  v0 := 0xAA
  save v0
  i := scratchpad-plus-16
  load v0
  expect-v0 0xAA

  i := scratchpad
  vF := 16
  i += vF
  v0 := 0x55
  save v0
  i := scratchpad-plus-16
  load v0
  expect-v0 0x55

  loop again

:segment data

: flags-no-carry
  str "HAPPY" 0
: flags-carry
  str "CARRY" 0
: flags-other
  str "OTHER" 0

:include "../../pictures/version.png"