cosmopolitan/libc/vga/writev-vga.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ This is free and unencumbered software released into the public domain.      │
│                                                                              │
│ Anyone is free to copy, modify, publish, use, compile, sell, or              │
│ distribute this software, either in source code form or as a compiled        │
│ binary, for any purpose, commercial or non-commercial, and by any            │
│ means.                                                                       │
│                                                                              │
│ In jurisdictions that recognize copyright laws, the author or authors        │
│ of this software dedicate any and all copyright interest in the              │
│ software to the public domain. We make this dedication for the benefit       │
│ of the public at large and to the detriment of our heirs and                 │
│ successors. We intend this dedication to be an overt act of                  │
│ relinquishment in perpetuity of all present and future rights to this        │
│ software under copyright law.                                                │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,              │
│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF           │
│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.       │
│ IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR            │
│ OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,        │
│ ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR        │
│ OTHER DEALINGS IN THE SOFTWARE.                                              │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/struct/fd.internal.h"
#include "libc/calls/struct/iovec.h"
#include "libc/calls/struct/iovec.internal.h"
#include "libc/vga/vga.internal.h"
#include "libc/runtime/pc.internal.h"
#include "libc/str/str.h"

#ifdef VGA_USE_WCS
static wchar_t vga_wcs[VGA_TTY_HEIGHT * VGA_TTY_WIDTH];
#else
static wchar_t * const vga_wcs = NULL;
#endif

struct Tty _vga_tty;

ssize_t sys_writev_vga(struct Fd *fd, const struct iovec *iov, int iovlen) {
  size_t i, wrote = 0;
  ssize_t res = 0;
  for (i = 0; i < iovlen; ++i) {
    void *output = iov[i].iov_base;
    size_t len = iov[i].iov_len;
    res = _TtyWrite(&_vga_tty, output, len);
    if (res < 0)
      break;
    wrote += res;
    if (res != len)
      return wrote;
  }
  if (!wrote)
    return res;
  return wrote;
}

__attribute__((__constructor__)) static textstartup void _vga_init(void) {
  void * const vid_buf = (void *)(BANE + 0xb8000ull);
  /*
   * Get the initial cursor position from the BIOS data area.  Also get
   * the height (in scan lines) of each character; this is used to set the
   * cursor shape.
   */
  typedef struct {
    unsigned char col, row;
  } bios_curs_pos_t;
  bios_curs_pos_t pos = *(bios_curs_pos_t *)(BANE + 0x0450ull);
  uint8_t chr_ht = *(uint8_t *)(BANE + 0x0485ull),
          chr_ht_hi = *(uint8_t *)(BANE + 0x0486ull);
  if (chr_ht_hi != 0 || chr_ht > 32)
    chr_ht = 32;
  /*
   * Initialize our tty structure from the current screen contents, current
   * cursor position, & character height.
   */
  _StartTty(&_vga_tty, VGA_TTY_HEIGHT, VGA_TTY_WIDTH, pos.row, pos.col,
            chr_ht, vid_buf, vga_wcs);
}