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package tests
import (
"testing"
"crecher.net/gones/v2/nes"
)
func fillPage(n *nes.Console, page uint8) {
for i := 0; i < 256; i++ {
n.Write(uint16(page)<<8|uint16(i), uint8(i))
}
}
func TestOAMDMACopiesPage(t *testing.T) {
n := newTestConsole(t)
fillPage(n, 0x02)
n.Write(0x4014, 0x02)
for i := 0; i < 256; i++ {
if n.PPU.OAM[i] != uint8(i) {
t.Fatalf("OAM[%d] = %d, want %d", i, n.PPU.OAM[i], i)
}
}
}
func TestOAMDMAStartsAtOAMAddr(t *testing.T) {
n := newTestConsole(t)
fillPage(n, 0x03)
n.Write(0x2003, 0x10)
n.Write(0x4014, 0x03)
// source byte 0 lands at OAM[0x10], and the copy wraps around
for _, i := range []int{0, 1, 0xF0, 0xFF} {
if got := n.PPU.OAM[(0x10+i)&0xFF]; got != uint8(i) {
t.Errorf("OAM[0x%02X] = %d, want %d", (0x10+i)&0xFF, got, i)
}
}
}
// runs `lda ; sta $4014` from RAM and returns the cycles the sta step took
func dmaStepCycles(t *testing.T, lda []uint8) int {
t.Helper()
n := newTestConsole(t)
prog := append(lda, 0x8D, 0x14, 0x40) // sta $4014
for i, b := range prog {
n.Write(0x0200+uint16(i), b)
}
n.Write(0x0000, 0x02) // for the zero page lda
n.CPU.PC = 0x0200
n.Step()
return n.Step()
}
func TestOAMDMAStallCycles(t *testing.T) {
// reset leaves the cpu at 7 cycles
// lda #imm (2): sta ends on cycle 13, odd -> 4 + 514
if got := dmaStepCycles(t, []uint8{0xA9, 0x02}); got != 518 {
t.Errorf("odd start: sta step = %d cycles, want 518", got)
}
// lda zp (3): sta ends on cycle 14, even -> 4 + 513
if got := dmaStepCycles(t, []uint8{0xA5, 0x00}); got != 517 {
t.Errorf("even start: sta step = %d cycles, want 517", got)
}
}
func TestOAMDMAAdvancesCPUCycles(t *testing.T) {
n := newTestConsole(t)
for i, b := range []uint8{0xA9, 0x02, 0x8D, 0x14, 0x40} {
n.Write(0x0200+uint16(i), b)
}
n.CPU.PC = 0x0200
n.Step()
n.Step()
if n.CPU.Cycles != 7+2+4+514 {
t.Errorf("CPU.Cycles = %d, want %d", n.CPU.Cycles, 7+2+4+514)
}
}
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