video.c

#include <am.h>
#include <x86.h>
#include <amdev.h>
#include <klib.h>

static uint32_t* const fb __attribute__((used)) = (uint32_t *)0x40000;

size_t video_read(uintptr_t reg, void *buf, size_t size) {
  const uint32_t SCREEN_PORT = 0x100;
  switch (reg) {
    case _DEVREG_VIDEO_INFO: {
      _VideoInfoReg *info = (_VideoInfoReg *)buf;
      uint32_t screen = inl(SCREEN_PORT);
      info->width = screen >> 16;
      info->height = screen << 16 >> 16;
      return sizeof(_VideoInfoReg);
    }
  }
  return 0;
}

size_t video_write(uintptr_t reg, void *buf, size_t size) {
  switch (reg) {
    case _DEVREG_VIDEO_FBCTL: {
      _FBCtlReg *ctl = (_FBCtlReg *)buf;
      for(int i = 0; i < ctl->h; ++i) {
        memcpy(fb+(ctl->y+i)*screen_width()+ctl->x,ctl->pixels+i*ctl->w,ctl->w*4);
      }
      if (ctl->sync) {
        // do nothing, hardware syncs.
      }
      return sizeof(_FBCtlReg);
    }
  }
  return 0;
}

void vga_init() {
}