Video simulator

[suarezvictor]

This is the source for the video simulator I announced on twitter: https://twitter.com/suarezvictor/status/1443288849468231692
For compiling original pattern generator test_pattern.c as is (and show it on screen when USE_VERILATOR macro not defined) small changes are needed to get full C and PipelineC compatibility (see #10 ). All referenced headers of PipelineC not found could be left empty, except the new "bitregs.h" that was posted on #20, which defines uintN_t and operations on such.

The no verilator version achieves about 33 FPS for 640x480 (44 with the hack for using native sizes for integers regardless asking for smaller sizes). For the verilated version, I wasn't able to test on less than 1920x1080 as cause of the current GHDL memory errors. At such high resolution it runs at about 4 FPS. Based on this, a cycle-to-cycle comparison can be done as explained in #21, or a switch between versions at the press of a key.

There's an algorithm to automatically detect horizontal/vertical blanking periods that may be avoided if the "active" signal is exported. Maybe this algorithm can be optimized, or also run a first frame to determine resolution before window creation.

Command to run is: clang++ -O3 -I. -I/usr/share/verilator/include main.cpp -o vtop -lSDL2
Alternatively, g++ also works. If using verilator-generated makefiles, it needs some way of passing "-lSDL2" linker command and changes for replacing the #includes for .cpp files to the corresponding headers.

/*
(C) 2021 Victor Suarez Rovere <suarezvictor@gmail.com>
LICENSE: GPL 3.0

$ verilator -Wall -cc top/top.v
$ clang++ -O3 -I. -I/usr/share/verilator/include main.cpp -o vtop -lSDL2
*/
  
#include <SDL2/SDL.h>

#define USE_VERILATOR

#ifndef USE_VERILATOR
#include "bitregs.h"

#define WIRE_WRITE(a,b,c)
#define WIRE_READ(a,b,c)
#define DEBUG_OUTPUT_DECL(a,b)
#define MAIN_MHZ(a,b)
#define SKIP_DEBUG_OUTPUT

//VGA pattern generation specifics
uint4_t debug_vga_red;
uint4_t debug_vga_green;
uint4_t debug_vga_blue;
uint1_t debug_vsync;
uint1_t debug_hsync;
typedef int app_to_vga_t_array_1_t, app_to_pmod_jc_t_array_1_t, app_to_pmod_jb_t_array_1_t;

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wparentheses" //for & and | operator precedence warning
#include "../examples/arty/src/vga/test_pattern.c"
#pragma clang diagnostic pop

#else
// screen dimensions
#define FRAME_WIDTH 1920
#define FRAME_HEIGHT 1080
#define V_POL 1
#define H_POL 1

#include "verilated.cpp" //verilator library
#include "obj_dir/Vtop.cpp" //generated by verilator
#include "obj_dir/Vtop__Syms.cpp" //generated by verilator

#define clk clk_25p0 //clk_148p5 for 1920x1080
#define _vga_red vga_red_DEBUG_OUTPUT_MAIN_return_output
#define _vga_green vga_green_DEBUG_OUTPUT_MAIN_return_output
#define _vga_blue vga_blue_DEBUG_OUTPUT_MAIN_return_output
#define _vsync vsync_DEBUG_OUTPUT_MAIN_return_output
#define _hsync hsync_DEBUG_OUTPUT_MAIN_return_output
#endif

bool fb_init(unsigned hres, unsigned vres);
void fb_update();
bool fb_should_quit();
void fb_deinit();
struct pixel_t { uint8_t a, b, g, r; };
pixel_t pixelbuf[FRAME_HEIGHT][FRAME_WIDTH];
inline void fb_setpixel(pixel_t *p, uint8_t r, uint8_t g, uint8_t b) { p->a = 0xFF; p->b = b; p->g = g; p->r = r; }
inline void fb_setpixel(unsigned x, unsigned y, uint8_t r, uint8_t g, uint8_t b) { fb_setpixel(&pixelbuf[y][x], r, g, b); }
inline uint64_t higres_ticks() { return SDL_GetPerformanceCounter(); }
inline uint64_t higres_ticks_freq() { return SDL_GetPerformanceFrequency(); }

int main()
{
#ifdef USE_VERILATOR
    Vtop* g_top = new Vtop;
#endif
    if(!fb_init(FRAME_WIDTH, FRAME_HEIGHT))
        return 1;

    uint64_t frame = 0;

    uint16_t x = 0, y = 0;
    unsigned hsync_width = FRAME_WIDTH, vsync_height = FRAME_HEIGHT; //initially out of range
    pixel_t *p = NULL;

    fb_update();
    uint64_t t0 = higres_ticks();

    uint4_t testval;
    for(;;)
    {
       if(x == 0 && y == 0 && fb_should_quit())
           break;

#ifdef USE_VERILATOR
       bool vs = g_top->_vsync;
       bool hs = g_top->_hsync;
#else
       bool vs = debug_vsync;
       bool hs = debug_hsync;
#endif
       if(vs == V_POL)
       {
           if(y != 0)
           {
             hsync_width = x;
             vsync_height = y - FRAME_HEIGHT;
             x = 0; y = 0;
             p = &pixelbuf[0][0];
             fb_update();
             ++frame;
           }
       }
       else if(hs == H_POL)
       {
           if(x != 0)
           {
              ++y;
              x = 0;
              if(y >= vsync_height && y < FRAME_HEIGHT + vsync_height)
                p = &pixelbuf[y-vsync_height][0];
              else
                p = NULL;
           }
       }
       else
       {
         if(p != NULL && x >= hsync_width && x < FRAME_WIDTH+hsync_width)
         {
#ifdef USE_VERILATOR
           uint8_t r = g_top->_vga_red;
           uint8_t g = g_top->_vga_green;
           uint8_t b = g_top->_vga_blue;
#else
           uint8_t r = debug_vga_red;
           uint8_t g = debug_vga_green;
           uint8_t b = debug_vga_blue;
#endif
           fb_setpixel(p++, r << 4, g << 4, b << 4);
         }
         ++x; //16 bit value that can wrap around if no hsync pulses comes
       }

#ifdef USE_VERILATOR
       g_top->clk = 0;
       g_top->eval();
       g_top->clk = 1;
       g_top->eval();
#else
#if 1
       app();
#else
       //reaches 107 FPS:
       debug_hsync=(x==FRAME_WIDTH) ? H_POL:!H_POL;
       debug_vsync=(y==FRAME_HEIGHT) ? V_POL:!V_POL;
       debug_vga_red = x+y+frame;
#endif
#endif
    }

    float elapsed = float(higres_ticks()-t0)/higres_ticks_freq();
    printf("FPS: %.1f\n", frame/elapsed);

#ifdef USE_VERILATOR
    g_top->final();
#endif
    fb_deinit();
    return 0;
}

//code adapted from https://projectf.io/posts/verilog-sim-verilator-sdl/

SDL_Window*   sdl_window   = NULL;
SDL_Renderer* sdl_renderer = NULL;
SDL_Texture*  sdl_texture  = NULL;

bool fb_init(unsigned hres, unsigned vres)
{
    if(SDL_Init(SDL_INIT_VIDEO) < 0) {
        printf("SDL init failed.\n");
        return false;
    }

    sdl_window = SDL_CreateWindow("Verilated Framebuffer", SDL_WINDOWPOS_CENTERED,
        SDL_WINDOWPOS_CENTERED, hres, vres, SDL_WINDOW_SHOWN);
    if (!sdl_window) {
        printf("Window creation failed: %s\n", SDL_GetError());
        return false;
    }

    sdl_renderer = SDL_CreateRenderer(sdl_window, -1,
        SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
    if (!sdl_renderer) {
        printf("Renderer creation failed: %s\n", SDL_GetError());
        return false;
    }

    sdl_texture = SDL_CreateTexture(sdl_renderer, SDL_PIXELFORMAT_RGBA8888,
        SDL_TEXTUREACCESS_TARGET, hres, vres);
    if (!sdl_texture) {
        printf("Texture creation failed: %s\n", SDL_GetError());
        return false;
    }
    return true;
}

bool fb_should_quit()
{
    SDL_Event e;
    if (SDL_PollEvent(&e)) {
        if (e.type == SDL_QUIT) {
            return true;
        }
    }
    return false;
}

void fb_update()
{
    SDL_UpdateTexture(sdl_texture, NULL, pixelbuf, FRAME_WIDTH*sizeof(pixel_t));
    SDL_RenderClear(sdl_renderer);
    SDL_RenderCopy(sdl_renderer, sdl_texture, NULL, NULL);
    SDL_RenderPresent(sdl_renderer);
}

void fb_deinit()
{
    SDL_DestroyTexture(sdl_texture);
    SDL_DestroyRenderer(sdl_renderer);
    SDL_DestroyWindow(sdl_window);
    SDL_Quit();
}

[JulianKemmerer]

Wow an excellent example - cant wait to try it out!

Thinking perhaps the user could specify to the PipelineC tool an existing main.cpp to use (i.e. the one you just posted) instead of just generating a 10 cycle template main.cpp

[suarezvictor]

I think a default "simulation.cpp" on same director y as .c to process file will be ok El jue., 30 sep. 2021 17:07, Julian Kemmerer ***@***.***> escribió:

…

Wow an excellent example - cant wait to try it out! Thinking perhaps the user could specify to the PipelineC tool an existing main.cpp to use (i.e. the one you just posted) instead of just generating a 10 cycle template main.cpp — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#22 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACBHVWKAL4S34CTN7HDMNJ3UES7RBANCNFSM5FCWVFDQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.