. If you need to test, get your own ROM and use: .\convbin -i <name>.nes -o NESTESTR.8xv --iformat bin --oformat 8xv --name NESTESTR --archive
#include <stdlib.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <math.h>
#include <tice.h>
#include <time.h>
#include <graphx.h>
#include <keypadc.h>
#include <inttypes.h>
#include <fileioc.h>
#include <debug.h>
#include "gfx/NESP.h"
#define PULL mem(++S, 1, 0, 0)
#define PUSH(x) mem(S--, 1, x, 1);
#define OP16(x) \
break; \
case x: \
case x + 16:
// BGR565 palette. Used instead of RGBA32 to reduce source code size.
int scany, // Scanline Y
shift_at; // Attribute shift register
uint8_t *rom, *chrrom, // Points to the start of PRG/CHR ROM
prg[2], chr[2], // Current PRG/CHR banks
A, X, Y, P = 4, S = ~2, PCH, PCL, // CPU Registers
addr_lo, addr_hi, // Current instruction address
nomem, // 1 => current instruction doesn't write to memory
result, // Temp variable
val, // Current instruction value
cross, // 1 => page crossing occurred
tmp, tmp2, // Temp variables
ppumask, ppuctrl, ppustatus, // PPU registers
ppubuf, // PPU buffered reads
W, // Write toggle PPU register
fine_x, // X fine scroll offset, 0..7
opcode, // Current instruction opcode
nmi, // 1 => NMI occurred
ntb, // Nametable byte
ptb_lo, ptb_hi, // Pattern table low/high byte
vram[2048], // Nametable RAM
palette_ram[64], // Palette RAM
ram[8192], // CPU RAM
chrram[8192], // CHR RAM (only used for some games)
prgram[8192], // PRG RAM (only used for some games)
oam[256], // Object Attribute Memory (sprite RAM)
mask[] = {128, 64, 1, 2, // Masks used in branch instructions
1, 0, 0, 1, 4, 0, 0, 4, 0,
0, 64, 0, 8, 0, 0, 8}, // Masks used in SE*/CL* instructions.
keys, // Joypad shift register
mirror, // Current mirroring mode
mmc1_bits, mmc1_data, mmc1_ctrl, // Mapper 1 (MMC1) registers
chrbank0, chrbank1, prgbank, // Current PRG/CHR bank
(*rombuf)[1024 * 1024],
*key_state;
uint16_t T, V, // "Loopy" PPU registers
sum, // Sum used for ADC/SBC
dot, // Horizontal position of PPU, from 0..340
atb, // Attribute byte
shift_hi, shift_lo, // Pattern table shift registers
cycles; // Cycle count for current instruction
// Read a byte from CHR ROM or CHR RAM.
uint8_t *get_chr_byte(uint16_t a) {
return &chrrom[chr[a >> 12] << 12 | a & 4095];
}
// Read a byte from nametable RAM.
uint8_t *get_nametable_byte(uint16_t a) {
return &vram[!mirror ? a % 1024 // single bank 0
: mirror == 1 ? a % 1024 + 1024 // single bank 1
: mirror == 2 ? a & 2047 // vertical mirroring
: a / 2 & 1024 | a % 1024]; // horizontal mirroring
}
// If `write` is non-zero, writes `val` to the address `hi:lo`, otherwise reads
// a value from the address `hi:lo`.
uint8_t mem(uint8_t lo, uint8_t hi, uint8_t val, uint8_t write) {
uint16_t a = hi << 8 | lo;
switch (hi >> 4) {
case 0 ... 1: // $0000...$1fff RAM
return write ? ram[a] = val : ram[a];
case 2 ... 3: // $2000..$2007 PPU (mirrored)
lo &= 7;
// read/write $2007
if (lo == 7) {
tmp = ppubuf;
uint8_t *rom =
// Access CHR ROM or CHR RAM
V < 8192 ? !write || chrrom == chrram ? get_chr_byte(V) : &tmp2
// Access nametable RAM
: V < 16128 ? get_nametable_byte(V)
// Access palette RAM
: palette_ram + (uint8_t)((V & 19) == 16 ? V ^ 16 : V);
write ? *rom = val : (ppubuf = *rom);
V += ppuctrl & 4 ? 32 : 1;
V %= 16384;
return tmp;
}
if (write)
switch (lo) {
case 0: // $2000 ppuctrl
ppuctrl = val;
T = T & 62463 | val % 4 << 10;
break;
case 1: // $2001 ppumask
ppumask = val;
break;
case 5: // $2005 ppuscroll
T = (W ^= 1) ? fine_x = val & 7,
T & ~31 | val / 8 : T & 35871 | val % 8 << 12 | (val & 248) * 4;
break;
case 6: // $2006 ppuaddr
T = (W ^= 1) ? T & 255 | val % 64 << 8 : (V = T & ~255 | val);
}
if (lo == 2) // $2002 ppustatus
return tmp = ppustatus & 224, ppustatus &= 127, W = 0, tmp;
break;
case 4:
if (write && lo == 20) // $4014 OAM DMA
for (sum = 256; sum--;)
oam[sum] = mem(sum, val, 0, 0);
// $4016 Joypad 1
return (lo == 22) ? write ? keys = ((kb_Data[7] & kb_Right) * 8 +
(kb_Data[7] & kb_Left) * 4 +
(kb_Data[7] & kb_Down) * 2 +
(kb_Data[7] & kb_Up)) *
16 +
(kb_Data[6] & kb_Clear) * 8 +
(kb_Data[5] & kb_Vars) * 4 +
(kb_2nd & kb_Data[1]) * 2 +
(kb_Alpha & kb_Data[2])
: (tmp = keys & 1, keys /= 2, tmp)
: 0;
case 6 ... 7: // $6000...$7fff PRG RAM
return write ? prgram[a & 8191] = val : prgram[a & 8191];
case 8 ... 15: // $8000...$ffff ROM
// handle mmc1 writes
if (write)
switch ((*rombuf)[6] >> 4) {
case 7: // mapper 7
mirror = !(val / 16);
*prg = val = val % 8 * 2;
prg[1] = val + 1;
break;
case 3: // mapper 3
*chr = val = val % 4 * 2;
chr[1] = val + 1;
break;
case 2: // mapper 2
*prg = val & 31;
break;
case 1: // mapper 1
if (val & 128) {
mmc1_bits = 5, mmc1_data = 0, mmc1_ctrl |= 12;
} else if (mmc1_data = mmc1_data / 2 | val << 4 & 16, !--mmc1_bits) {
mmc1_bits = 5, tmp = a >> 13;
*(tmp == 4 ? mirror = mmc1_data & 3, &mmc1_ctrl
: tmp == 5 ? &chrbank0
: tmp == 6 ? &chrbank1
: &prgbank) = mmc1_data;
// Update CHR banks.
*chr = chrbank0 & ~!(mmc1_ctrl & 16);
chr[1] = mmc1_ctrl & 16 ? chrbank1 : chrbank0 | 1;
// Update PRG banks.
tmp = mmc1_ctrl / 4 & 3;
*prg = tmp == 2 ? 0 : tmp == 3 ? prgbank : prgbank & ~1;
prg[1] = tmp == 2 ? prgbank : tmp == 3 ? (*rombuf)[4] - 1 : prgbank | 1;
}
}
return rom[prg[(a >> 14) - 2] << 14 | a & 16383];
}
return ~0;
}
// Read a byte at address `PCH:PCL` and increment PC.
uint8_t read_pc() {
val = mem(PCL, PCH, 0, 0);
!++PCL ? ++PCH : 0;
return val;
}
// Set N (negative) and Z (zero) flags of `P` register, based on `val`.
uint8_t set_nz(uint8_t val) { return P = P & ~130 | val & 128 | !val * 2; }
int main(void) {
uint8_t var = ti_Open("NESTESTR", "r");
if (var == 0)
{
os_SetCursorPos(0, 0);
os_PutStrFull("ERROR OPENING NESTEST");
while (!os_GetCSC());
exit(0);
}
if (NESP_init == 0)
{
os_SetCursorPos(0, 0);
os_PutStrFull("MISSING PALETTE");
while (!os_GetCSC());
exit(0);
}
rombuf = ti_GetDataPtr(var);
ti_Close(var);
// Start PRG0 after 16-byte header.
rom = *rombuf + 16;
// PRG1 is the last bank. `rombuf[4]` is the number of 16k PRG banks.
prg[1] = (*rombuf)[4] - 1;
// CHR0 ROM is after all PRG data in the file. `rombuf[5]` is the number of
// 8k CHR banks. If it is zero, assume the game uses CHR RAM.
chrrom = (*rombuf)[5] ? rom + ((prg[1] + 1) << 14) : chrram;
// CHR1 is the last 4k bank.
chr[1] = ((*rombuf)[5] ? (*rombuf)[5] : 1) * 2 - 1;
// Bit 0 of `rombuf[6]` is 0=>horizontal mirroring, 1=>vertical mirroring.
mirror = !((*rombuf)[6] & 1) + 2;
// Start at address in reset vector, at $FFFC.
PCL = mem(~3, ~0, 0, 0);
PCH = mem(~2, ~0, 0, 0);
gfx_Begin();
gfx_SetDrawBuffer(); // draw to the buffer to avoid rendering artifacts
gfx_ZeroScreen();
for (;;) {
cycles = nomem = 0;
if (nmi)
goto nmi;
kb_Scan();
if (kb_Data[1] & kb_Del)
{
break;
}
switch ((opcode = read_pc()) & 31) {
case 0:
dbg_printf("Case 0", dot);
if (opcode & 128) { // LDY/CPY/CPX imm
read_pc();
nomem = 1;
goto nomemop;
}
switch (opcode >> 5) {
case 0: // BRK or NMI
!++PCL ? ++PCH : 0;
nmi:
PUSH(PCH)
PUSH(PCL)
PUSH(P | 32)
// BRK vector is $ffff, NMI vector is $fffa
PCL = mem(~1 - nmi * 4, ~0, 0, 0);
PCH = mem(~0 - nmi * 4, ~0, 0, 0);
cycles++;
nmi = 0;
break;
case 1: // JSR
result = read_pc();
PUSH(PCH)
PUSH(PCL)
PCH = read_pc();
PCL = result;
break;
case 2: // RTI
P = PULL & ~32;
PCL = PULL;
PCH = PULL;
break;
case 3: // RTS
PCL = PULL;
PCH = PULL;
!++PCL ? ++PCH : 0;
break;
}
cycles += 4;
break;
case 16: // BPL, BMI, BVC, BVS, BCC, BCS, BNE, BEQ
read_pc();
if (!(P & mask[opcode >> 6 & 3]) ^ opcode / 32 & 1) {
if (cross = PCL + (int8_t)val >> 8)
PCH += cross, cycles++;
cycles++, PCL += (int)val;
}
dbg_printf("Case 16", dot);
OP16(8)
dbg_printf("OP16 8", dot);
switch (opcode >>= 4) {
case 0: // PHP
PUSH(P | 48)
cycles++;
break;
case 2: // PLP
P = PULL & ~16;
cycles += 2;
break;
case 4: // PHA
PUSH(A)
cycles++;
break;
case 6: // PLA
set_nz(A = PULL);
cycles += 2;
break;
case 8: // DEY
set_nz(--Y);
break;
case 9: // TYA
set_nz(A = Y);
break;
case 10: // TAY
set_nz(Y = A);
break;
case 12: // INY
set_nz(++Y);
break;
case 14: // INX
set_nz(++X);
break;
default: // CLC, SEC, CLI, SEI, CLV, CLD, SED
P = P & ~mask[opcode + 3] | mask[opcode + 4];
break;
}
OP16(10)
dbg_printf("OP16 10", dot);
switch (opcode >> 4) {
case 8: // TXA
set_nz(A = X);
break;
case 9: // TXS
S = X;
break;
case 10: // TAX
set_nz(X = A);
break;
case 11: // TSX
set_nz(X = S);
break;
case 12: // DEX
set_nz(--X);
break;
case 14: // NOP
break;
default: // ASL/ROL/LSR/ROR A
nomem = 1;
val = A;
goto nomemop;
}
break;
case 1: // X-indexed, indirect
read_pc();
val += X;
addr_lo = mem(val, 0, 0, 0);
addr_hi = mem(val + 1, 0, 0, 0);
cycles += 4;
goto opcode;
case 4 ... 6: // Zeropage
addr_lo = read_pc();
addr_hi = 0;
cycles++;
goto opcode;
case 2: case 9: // Immediate
read_pc();
nomem = 1;
goto nomemop;
case 12 ... 14: // Absolute
addr_lo = read_pc();
addr_hi = read_pc();
cycles += 2;
goto opcode;
case 17: // Zeropage, Y-indexed
addr_lo = mem(read_pc(), 0, 0, 0);
addr_hi = mem(val + 1, 0, 0, 0);
val = Y;
tmp = opcode == 145; // STA always uses extra cycle.
cycles++;
goto cross;
case 20 ... 22: // Zeropage, X-indexed
addr_lo = read_pc() + ((opcode & 214) == 150 ? Y : X); // LDX/STX use Y
addr_hi = 0;
cycles += 2;
goto opcode;
case 25: // Absolute, Y-indexed.
addr_lo = read_pc();
addr_hi = read_pc();
val = Y;
tmp = opcode == 153; // STA always uses extra cycle.
goto cross;
case 28 ... 30: // Absolute, X-indexed.
addr_lo = read_pc();
addr_hi = read_pc();
val = opcode == 190 ? Y : X; // LDX uses Y
tmp = opcode == 157 || // STA always uses extra cycle.
// ASL/ROL/LSR/ROR/INC/DEC all uses extra cycle.
opcode % 16 == 14 && opcode != 190;
// fallthrough
cross:
addr_hi += cross = addr_lo + val > 255;
addr_lo += val;
cycles += 2 + tmp | cross;
// fallthrough
opcode:
// Read from the given address into `val` for convenience below, except
// for the STA/STX/STY instructions, and JMP.
(opcode & 224) != 128 &&opcode != 76 ? val = mem(addr_lo, addr_hi, 0, 0)
: 0;
nomemop:
switch (opcode & 243) {
OP16(1) set_nz(A |= val); // ORA
OP16(33) set_nz(A &= val); // AND
OP16(65) set_nz(A ^= val); // EOR
OP16(225) // SBC
val = ~val;
goto add;
OP16(97) // ADC
add:
sum = A + val + (P & 1);
P = P & ~65 | sum > 255 | (~(A ^ val) & (val ^ sum) & 128) / 2;
set_nz(A = sum);
OP16(2) // ASL
result = val * 2;
P = P & ~1 | val / 128;
goto memop;
OP16(34) // ROL
result = val * 2 | P & 1;
P = P & ~1 | val / 128;
goto memop;
OP16(66) // LSR
result = val / 2;
P = P & ~1 | val & 1;
goto memop;
OP16(98) // ROR
result = val / 2 | P << 7;
P = P & ~1 | val & 1;
goto memop;
OP16(194) // DEC
result = val - 1;
goto memop;
OP16(226) // INC
result = val + 1;
// fallthrough
memop:
set_nz(result);
// Write result to A or back to memory.
nomem ? A = result : (cycles += 2, mem(addr_lo, addr_hi, result, 1));
break;
case 32: // BIT
P = P & 61 | val & 192 | !(A & val) * 2;
break;
case 64: // JMP
PCL = addr_lo;
PCH = addr_hi;
cycles--;
break;
case 96: // JMP indirect
PCL = val;
PCH = mem(addr_lo + 1, addr_hi, 0, 0);
cycles++;
OP16(160) set_nz(Y = val); // LDY
OP16(161) set_nz(A = val); // LDA
OP16(162) set_nz(X = val); // LDX
OP16(128) result = Y; goto store; // STY
OP16(129) result = A; goto store; // STA
OP16(130) result = X; // STX
store:
mem(addr_lo, addr_hi, result, 1);
OP16(192) result = Y; goto cmp; // CPY
OP16(193) result = A; goto cmp; // CMP
OP16(224) result = X; // CPX
cmp:
P = P & ~1 | result >= val;
set_nz(result - val);
break;
}
}
// Update PPU, which runs 3 times faster than CPU. Each CPU instruction
// takes at least 2 cycles.
for (tmp = cycles * 3 + 6; tmp--;) {
if (ppumask & 24) { // If background or sprites are enabled.
if (scany < 240) {
if (dot < 256 || dot > 319) {
switch (dot & 7) {
case 1: // Read nametable byte.
ntb = *get_nametable_byte(V);
break;
case 3: // Read attribute byte.
atb = (*get_nametable_byte(960 | V & 3072 | V >> 4 & 56 |
V / 4 & 7) >>
(V >> 5 & 2 | V / 2 & 1) * 2) &
3;
atb |= atb * 4;
atb |= atb << 4;
atb |= atb << 8;
break;
case 5: // Read pattern table low byte.
ptb_lo = *get_chr_byte(ppuctrl << 8 & 4096 | ntb << 4 | V >> 12);
break;
case 7: // Read pattern table high byte.
ptb_hi =
*get_chr_byte(ppuctrl << 8 & 4096 | ntb << 4 | V >> 12 | 8);
// Increment horizontal VRAM read address.
V = (V & 31) == 31 ? V & ~31 ^ 1024 : V + 1;
break;
}
// Draw a pixel to the framebuffer.
if ((uint16_t)scany < 240 && dot < 256) {
// Read color and palette from shift registers.
uint8_t color = shift_hi >> 14 - fine_x & 2 |
shift_lo >> 15 - fine_x & 1,
palette_temp = shift_at >> 28 - fine_x * 2 & 12;
// If sprites are enabled.
if (ppumask & 16)
// Loop through all sprites.
for (uint8_t *sprite = oam; sprite < oam + 256; sprite += 4) {
uint16_t sprite_h = ppuctrl & 32 ? 16 : 8,
sprite_x = dot - sprite[3],
sprite_y = scany - *sprite - 1,
sx = sprite_x ^ (sprite[2] & 64 ? 0 : 7),
sy = sprite_y ^ (sprite[2] & 128 ? sprite_h - 1 : 0);
if (sprite_x < 8 && sprite_y < sprite_h) {
uint16_t sprite_tile = sprite[1],
sprite_addr = ppuctrl & 32
// 8x16 sprites
? sprite_tile % 2 << 12 |
(sprite_tile & ~1) << 4 |
(sy & 8) * 2 | sy & 7
// 8x8 sprites
: (ppuctrl & 8) << 9 |
sprite_tile << 4 | sy & 7,
sprite_color =
*get_chr_byte(sprite_addr + 8) >> sx << 1 & 2 |
*get_chr_byte(sprite_addr) >> sx & 1;
// Only draw sprite if color is not 0 (transparent)
if (sprite_color) {
// Don't draw sprite if BG has priority.
!(sprite[2] & 32 && color)
? color = sprite_color,
palette_temp = 16 | sprite[2] * 4 & 12 : 0;
// Maybe set sprite0 hit flag.
sprite == oam &&color ? ppustatus |= 64 : 0;
break;
}
}
}
gfx_SetColor(palette_ram[color ? palette_temp | color : 0]);
// Write pixel to framebuffer. Always use palette 0 for color 0.
gfx_SetPixel(dot + 32, scany);
}
// Update shift registers every cycle.
dot < 336 ? shift_hi *= 2, shift_lo *= 2, shift_at *= 4 : 0;
// Reload shift registers every 8 cycles.
dot % 8 == 7 ? shift_hi |= ptb_hi, shift_lo |= ptb_lo,
shift_at |= atb : 0;
}
// Increment vertical VRAM address.
dot == 256 ? V = ((V & 7 << 12) != 7 << 12 ? V + 4096
: (V & 992) == 928 ? V & 35871 ^ 2048
: (V & 992) == 992 ? V & 35871
: V & 35871 | V + 32 & 992) &
// Reset horizontal VRAM address to T value.
~1055 |
T & 1055
: 0;
}
// Reset vertical VRAM address to T value.
scany == -1 &&dot > 279 &&dot < 305 ? V = V & 33823 | T & 31712 : 0;
}
if (scany == 241 && dot == 1) {
// If NMI is enabled, trigger NMI.
ppuctrl & 128 ? nmi = 1 : 0;
ppustatus |= 128;
gfx_BlitBuffer();
dbg_printf("Draw", dot);
}
// Clear ppustatus.
scany == -1 &&dot == 1 ? ppustatus = 0 : 0;
// Increment to next dot/scany. 341 dots per scanline, 262 scanlines per
// frame. Scanline 261 is represented as -1.
++dot == 341 ? dot = 0, scany = scany == 260 ? -1 : scany + 1 : 0;
}
}
gfx_End();
exit(0);
}
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