/*
 * galaksija-display - Galaksija (1983) 32x16 text video rendered from its
 * memory-mapped video RAM (Phase 3, project/multichip-bus/). Passive BUS SNOOP:
 * watches WR + address + data; on a write into 0x2800-0x2BFF it draws the
 * character into a 256x128 framebuffer. Never drives the bus.
 *
 * Galaksija stores ASCII codes in video RAM (it writes "READY" as 0x52,0x45,..).
 * Rendered with the public-domain IBM/VGA 8x8 font (font8x8 by Daniel Hepper /
 * Marcel Sondaar), green-on-black phosphor. font8x8: 1 byte/row, bit 0 (LSB) =
 * leftmost pixel, 1 = lit. The framebuffer is BLITTED on a ~30 fps timer (not
 * on every character write) so a fast clear-screen burst does not flood the
 * host canvas with repaints.
 */
#include "velxio-chip.h"
#include <stdint.h>
#include <stdbool.h>
#define COLS 32
#define ROWS 16
#define FB_W (COLS*8)
#define FB_H (ROWS*8)
static const uint8_t font8x8[1024] = {
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x18,0x3c,0x3c,0x18,0x18,0x00,0x18,0x00,
    0x36,0x36,0x00,0x00,0x00,0x00,0x00,0x00,0x36,0x36,0x7f,0x36,0x7f,0x36,0x36,0x00,
    0x0c,0x3e,0x03,0x1e,0x30,0x1f,0x0c,0x00,0x00,0x63,0x33,0x18,0x0c,0x66,0x63,0x00,
    0x1c,0x36,0x1c,0x6e,0x3b,0x33,0x6e,0x00,0x06,0x06,0x03,0x00,0x00,0x00,0x00,0x00,
    0x18,0x0c,0x06,0x06,0x06,0x0c,0x18,0x00,0x06,0x0c,0x18,0x18,0x18,0x0c,0x06,0x00,
    0x00,0x66,0x3c,0xff,0x3c,0x66,0x00,0x00,0x00,0x0c,0x0c,0x3f,0x0c,0x0c,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x0c,0x0c,0x06,0x00,0x00,0x00,0x3f,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x0c,0x0c,0x00,0x60,0x30,0x18,0x0c,0x06,0x03,0x01,0x00,
    0x3e,0x63,0x73,0x7b,0x6f,0x67,0x3e,0x00,0x0c,0x0e,0x0c,0x0c,0x0c,0x0c,0x3f,0x00,
    0x1e,0x33,0x30,0x1c,0x06,0x33,0x3f,0x00,0x1e,0x33,0x30,0x1c,0x30,0x33,0x1e,0x00,
    0x38,0x3c,0x36,0x33,0x7f,0x30,0x78,0x00,0x3f,0x03,0x1f,0x30,0x30,0x33,0x1e,0x00,
    0x1c,0x06,0x03,0x1f,0x33,0x33,0x1e,0x00,0x3f,0x33,0x30,0x18,0x0c,0x0c,0x0c,0x00,
    0x1e,0x33,0x33,0x1e,0x33,0x33,0x1e,0x00,0x1e,0x33,0x33,0x3e,0x30,0x18,0x0e,0x00,
    0x00,0x0c,0x0c,0x00,0x00,0x0c,0x0c,0x00,0x00,0x0c,0x0c,0x00,0x00,0x0c,0x0c,0x06,
    0x18,0x0c,0x06,0x03,0x06,0x0c,0x18,0x00,0x00,0x00,0x3f,0x00,0x00,0x3f,0x00,0x00,
    0x06,0x0c,0x18,0x30,0x18,0x0c,0x06,0x00,0x1e,0x33,0x30,0x18,0x0c,0x00,0x0c,0x00,
    0x3e,0x63,0x7b,0x7b,0x7b,0x03,0x1e,0x00,0x0c,0x1e,0x33,0x33,0x3f,0x33,0x33,0x00,
    0x3f,0x66,0x66,0x3e,0x66,0x66,0x3f,0x00,0x3c,0x66,0x03,0x03,0x03,0x66,0x3c,0x00,
    0x1f,0x36,0x66,0x66,0x66,0x36,0x1f,0x00,0x7f,0x46,0x16,0x1e,0x16,0x46,0x7f,0x00,
    0x7f,0x46,0x16,0x1e,0x16,0x06,0x0f,0x00,0x3c,0x66,0x03,0x03,0x73,0x66,0x7c,0x00,
    0x33,0x33,0x33,0x3f,0x33,0x33,0x33,0x00,0x1e,0x0c,0x0c,0x0c,0x0c,0x0c,0x1e,0x00,
    0x78,0x30,0x30,0x30,0x33,0x33,0x1e,0x00,0x67,0x66,0x36,0x1e,0x36,0x66,0x67,0x00,
    0x0f,0x06,0x06,0x06,0x46,0x66,0x7f,0x00,0x63,0x77,0x7f,0x7f,0x6b,0x63,0x63,0x00,
    0x63,0x67,0x6f,0x7b,0x73,0x63,0x63,0x00,0x1c,0x36,0x63,0x63,0x63,0x36,0x1c,0x00,
    0x3f,0x66,0x66,0x3e,0x06,0x06,0x0f,0x00,0x1e,0x33,0x33,0x33,0x3b,0x1e,0x38,0x00,
    0x3f,0x66,0x66,0x3e,0x36,0x66,0x67,0x00,0x1e,0x33,0x07,0x0e,0x38,0x33,0x1e,0x00,
    0x3f,0x2d,0x0c,0x0c,0x0c,0x0c,0x1e,0x00,0x33,0x33,0x33,0x33,0x33,0x33,0x3f,0x00,
    0x33,0x33,0x33,0x33,0x33,0x1e,0x0c,0x00,0x63,0x63,0x63,0x6b,0x7f,0x77,0x63,0x00,
    0x63,0x63,0x36,0x1c,0x1c,0x36,0x63,0x00,0x33,0x33,0x33,0x1e,0x0c,0x0c,0x1e,0x00,
    0x7f,0x63,0x31,0x18,0x4c,0x66,0x7f,0x00,0x1e,0x06,0x06,0x06,0x06,0x06,0x1e,0x00,
    0x03,0x06,0x0c,0x18,0x30,0x60,0x40,0x00,0x1e,0x18,0x18,0x18,0x18,0x18,0x1e,0x00,
    0x08,0x1c,0x36,0x63,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xff,
    0x0c,0x0c,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x1e,0x30,0x3e,0x33,0x6e,0x00,
    0x07,0x06,0x06,0x3e,0x66,0x66,0x3b,0x00,0x00,0x00,0x1e,0x33,0x03,0x33,0x1e,0x00,
    0x38,0x30,0x30,0x3e,0x33,0x33,0x6e,0x00,0x00,0x00,0x1e,0x33,0x3f,0x03,0x1e,0x00,
    0x1c,0x36,0x06,0x0f,0x06,0x06,0x0f,0x00,0x00,0x00,0x6e,0x33,0x33,0x3e,0x30,0x1f,
    0x07,0x06,0x36,0x6e,0x66,0x66,0x67,0x00,0x0c,0x00,0x0e,0x0c,0x0c,0x0c,0x1e,0x00,
    0x30,0x00,0x30,0x30,0x30,0x33,0x33,0x1e,0x07,0x06,0x66,0x36,0x1e,0x36,0x67,0x00,
    0x0e,0x0c,0x0c,0x0c,0x0c,0x0c,0x1e,0x00,0x00,0x00,0x33,0x7f,0x7f,0x6b,0x63,0x00,
    0x00,0x00,0x1f,0x33,0x33,0x33,0x33,0x00,0x00,0x00,0x1e,0x33,0x33,0x33,0x1e,0x00,
    0x00,0x00,0x3b,0x66,0x66,0x3e,0x06,0x0f,0x00,0x00,0x6e,0x33,0x33,0x3e,0x30,0x78,
    0x00,0x00,0x3b,0x6e,0x66,0x06,0x0f,0x00,0x00,0x00,0x3e,0x03,0x1e,0x30,0x1f,0x00,
    0x08,0x0c,0x3e,0x0c,0x0c,0x2c,0x18,0x00,0x00,0x00,0x33,0x33,0x33,0x33,0x6e,0x00,
    0x00,0x00,0x33,0x33,0x33,0x1e,0x0c,0x00,0x00,0x00,0x63,0x6b,0x7f,0x7f,0x36,0x00,
    0x00,0x00,0x63,0x36,0x1c,0x36,0x63,0x00,0x00,0x00,0x33,0x33,0x33,0x3e,0x30,0x1f,
    0x00,0x00,0x3f,0x19,0x0c,0x26,0x3f,0x00,0x38,0x0c,0x0c,0x07,0x0c,0x0c,0x38,0x00,
    0x18,0x18,0x18,0x00,0x18,0x18,0x18,0x00,0x07,0x0c,0x0c,0x38,0x0c,0x0c,0x07,0x00,
    0x6e,0x3b,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
};
typedef struct { vx_pin a[14]; vx_pin d[8]; vx_pin wr; int wr_last; vx_buffer fb; vx_timer paint; bool dirty; } chip_t;
static chip_t G;
static uint8_t fbpix[FB_W*FB_H*4];
static uint16_t read_addr(void){ uint16_t v=0; for(int i=0;i<14;i++) if(vx_pin_read(G.a[i])) v|=(1u<<i); return v; }
static uint8_t read_data(void){ uint8_t v=0; for(int i=0;i<8;i++) if(vx_pin_read(G.d[i])) v|=(1u<<i); return v; }
static void put_px(int x,int y,uint8_t lit){ if((unsigned)x<FB_W&&(unsigned)y<FB_H){ int o=(y*FB_W+x)*4; fbpix[o]=lit?0x33:0x00; fbpix[o+1]=lit?0xE0:0x12; fbpix[o+2]=lit?0x33:0x00; fbpix[o+3]=0xFF; } }
static void render_cell(int col,int row,uint8_t ch){ uint8_t c=ch&0x7f; for(int line=0;line<8;line++){ uint8_t bits=font8x8[c*8+line]; for(int px=0;px<8;px++) put_px(col*8+px,row*8+line,(bits>>px)&1);} G.dirty=true; }
static void on_wr(void* u, vx_pin p, int value){ (void)u;(void)p; if(G.wr_last==0&&value==1){ uint16_t a=read_addr(); if((a&0x3C00)==0x2800){ uint16_t off=a&0x3FF; int row=off/COLS,col=off%COLS; if(row<ROWS) render_cell(col,row,read_data()); } } G.wr_last=value; }
static void on_paint(void* u){ (void)u; if(G.dirty){ vx_buffer_write(G.fb,0,fbpix,sizeof(fbpix)); G.dirty=false; } }
void chip_setup(void){
  char name[4];
  for(int i=0;i<14;i++){ name[0]='A'; if(i<10){name[1]='0'+i;name[2]=0;} else {name[1]='1';name[2]='0'+(i-10);name[3]=0;} G.a[i]=vx_pin_register(name,VX_INPUT);}
  for(int i=0;i<8;i++){ name[0]='D';name[1]='0'+i;name[2]=0; G.d[i]=vx_pin_register(name,VX_INPUT);}
  G.wr=vx_pin_register("WR",VX_INPUT); G.wr_last=vx_pin_read(G.wr);
  uint32_t w,h; G.fb=vx_framebuffer_init(&w,&h);
  for(int i=0;i<FB_W*FB_H;i++){ fbpix[i*4]=0;fbpix[i*4+1]=0x12;fbpix[i*4+2]=0;fbpix[i*4+3]=0xFF; }
  vx_buffer_write(G.fb,0,fbpix,sizeof(fbpix)); G.dirty=false;
  vx_pin_watch(G.wr,VX_EDGE_BOTH,on_wr,0);
  G.paint=vx_timer_create(on_paint,0); vx_timer_start(G.paint,33000000ULL,true); /* ~30 fps blit */
}