Quick prototype for VGA console output in bare metal mode

Makefile

@@ -111,6 +111,7 @@ include libc/linux/linux.mk			# │  You can manipulate arrays
 include libc/tinymath/tinymath.mk		# │  You can issue raw system calls
 include third_party/compiler_rt/compiler_rt.mk	# │
 include libc/str/str.mk				# │
+include libc/vga/vga.mk				# │
 include third_party/xed/xed.mk			# │
 include third_party/zlib/zlib.mk		# │
 include libc/elf/elf.mk				# │
@@ -316,7 +317,8 @@ COSMOPOLITAN_OBJECTS =		\
 	LIBC_SYSV		\
 	LIBC_INTRIN		\
 	LIBC_NT_KERNEL32	\
-	LIBC_NEXGEN32E
+	LIBC_NEXGEN32E		\
+	LIBC_VGA
 
 COSMOPOLITAN_HEADERS =		\
 	APE			\
@@ -341,6 +343,7 @@ COSMOPOLITAN_HEADERS =		\
 	LIBC_TINYMATH		\
 	LIBC_X			\
 	LIBC_ZIPOS		\
+	LIBC_VGA		\
 	NET_HTTP		\
 	THIRD_PARTY_DLMALLOC	\
 	THIRD_PARTY_GDTOA	\

examples/examples.mk

@@ -66,6 +66,7 @@ EXAMPLES_DIRECTDEPS =								\
 	LIBC_THREAD								\
 	LIBC_TIME								\
 	LIBC_TINYMATH								\
+	LIBC_VGA								\
 	LIBC_X									\
 	LIBC_ZIPOS								\
 	NET_HTTP								\

examples/hello4.c

@@ -10,6 +10,8 @@
 #include "libc/math.h"
 #include "libc/stdio/stdio.h"
 
+STATIC_YOINK("vga_console");
+
 int main(int argc, char *argv[]) {
   volatile long double x = -.5;
   volatile long double y = 1.5;

libc/calls/calls.mk

@@ -51,7 +51,8 @@ LIBC_CALLS_A_DIRECTDEPS =				\
 	LIBC_STR					\
 	LIBC_STUBS					\
 	LIBC_SYSV_CALLS					\
-	LIBC_SYSV
+	LIBC_SYSV					\
+	LIBC_VGA
 
 LIBC_CALLS_A_DEPS :=					\
 	$(call uniq,$(foreach x,$(LIBC_CALLS_A_DIRECTDEPS),$($(x))))

libc/calls/writev-metal.c

@@ -19,10 +19,16 @@
 #include "libc/calls/struct/fd.internal.h"
 #include "libc/calls/struct/iovec.h"
 #include "libc/calls/struct/iovec.internal.h"
+#include "libc/intrin/weaken.h"
 #include "libc/sysv/errfuns.h"
+#include "libc/vga/vga.h"
 
 ssize_t sys_writev_metal(struct Fd *fd, const struct iovec *iov, int iovlen) {
   switch (fd->kind) {
+    case kFdConsole:
+      if (weaken(sys_writev_vga))
+        weaken(sys_writev_vga)(fd, iov, iovlen);
+      /* fallthrough */
     case kFdSerial:
       return sys_writev_serial(fd, iov, iovlen);
     default:

libc/intrin/g_fds.c

@@ -21,6 +21,7 @@
 #include "libc/intrin/pthread.h"
 #include "libc/intrin/pushpop.h"
 #include "libc/intrin/spinlock.h"
+#include "libc/intrin/weaken.h"
 #include "libc/nt/runtime.h"
 #include "libc/sysv/consts/o.h"
 
@@ -55,10 +56,17 @@ textstartup void InitializeFileDescriptors(void) {
   fds->f = 3;
   fds->p = fds->__init_p;
   if (IsMetal()) {
+    extern const char vga_console[];
     pushmov(&fds->f, 3ull);
-    fds->__init_p[0].kind = pushpop(kFdSerial);
-    fds->__init_p[1].kind = pushpop(kFdSerial);
-    fds->__init_p[2].kind = pushpop(kFdSerial);
+    if (weaken(vga_console)) {
+      fds->__init_p[0].kind = pushpop(kFdConsole);
+      fds->__init_p[1].kind = pushpop(kFdConsole);
+      fds->__init_p[2].kind = pushpop(kFdConsole);
+    } else {
+      fds->__init_p[0].kind = pushpop(kFdSerial);
+      fds->__init_p[1].kind = pushpop(kFdSerial);
+      fds->__init_p[2].kind = pushpop(kFdSerial);
+    }
     fds->__init_p[0].handle = VEIL("r", 0x3F8ull);
     fds->__init_p[1].handle = VEIL("r", 0x3F8ull);
     fds->__init_p[2].handle = VEIL("r", 0x3F8ull);

libc/libc.mk

@@ -30,6 +30,7 @@ o/$(MODE)/libc:	o/$(MODE)/libc/calls		\
 		o/$(MODE)/libc/thread		\
 		o/$(MODE)/libc/time		\
 		o/$(MODE)/libc/tinymath		\
+		o/$(MODE)/libc/vga		\
 		o/$(MODE)/libc/x		\
 		o/$(MODE)/libc/zipos		\
 		$(LIBC_CHECKS)

libc/vga/vga.h

@@ -0,0 +1,15 @@
+#ifndef COSMOPOLITAN_LIBC_VGA_VGA_H_
+#define COSMOPOLITAN_LIBC_VGA_VGA_H_
+
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+#include "libc/calls/struct/fd.internal.h"
+#include "libc/calls/struct/iovec.h"
+#include "libc/calls/struct/iovec.internal.h"
+
+COSMOPOLITAN_C_START_
+
+ssize_t sys_writev_vga(struct Fd *, const struct iovec *, int);
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_VGA_VGA_H_ */

libc/vga/vga.mk

@@ -0,0 +1,57 @@
+#-*-mode:makefile-gmake;indent-tabs-mode:t;tab-width:8;coding:utf-8-*-┐
+#───vi: set et ft=make ts=8 tw=8 fenc=utf-8 :vi───────────────────────┘
+
+PKGS += LIBC_VGA
+
+LIBC_VGA_ARTIFACTS += LIBC_VGA_A
+LIBC_VGA_A = o/$(MODE)/libc/vga/vga.a
+LIBC_VGA_A_FILES := $(wildcard libc/vga/*)
+LIBC_VGA_A_HDRS = $(filter %.h,$(LIBC_VGA_A_FILES))
+LIBC_VGA_A_SRCS_S = $(filter %.S,$(LIBC_VGA_A_FILES))
+LIBC_VGA_A_SRCS_C = $(filter %.c,$(LIBC_VGA_A_FILES))
+
+LIBC_VGA =						\
+	$(LIBC_VGA_A_DEPS)				\
+	$(LIBC_VGA_A)
+
+LIBC_VGA_A_SRCS =					\
+	$(LIBC_VGA_A_SRCS_S)				\
+	$(LIBC_VGA_A_SRCS_C)
+
+LIBC_VGA_A_OBJS =					\
+	$(LIBC_VGA_A_SRCS_S:%.S=o/$(MODE)/%.o)	\
+	$(LIBC_VGA_A_SRCS_C:%.c=o/$(MODE)/%.o)
+
+LIBC_VGA_A_CHECKS =					\
+	$(LIBC_VGA_A).pkg				\
+	$(LIBC_VGA_A_HDRS:%=o/$(MODE)/%.ok)
+
+LIBC_VGA_A_DIRECTDEPS =					\
+	LIBC_NEXGEN32E					\
+	LIBC_SYSV					\
+	LIBC_STR					\
+	LIBC_INTRIN					\
+	LIBC_STUBS
+
+LIBC_VGA_A_DEPS :=					\
+	$(call uniq,$(foreach x,$(LIBC_VGA_A_DIRECTDEPS),$($(x))))
+
+$(LIBC_VGA_A):libc/vga/					\
+		$(LIBC_VGA_A).pkg			\
+		$(LIBC_VGA_A_OBJS)
+
+$(LIBC_VGA_A).pkg:					\
+		$(LIBC_VGA_A_OBJS)			\
+		$(foreach x,$(LIBC_VGA_A_DIRECTDEPS),$($(x)_A).pkg)
+
+LIBC_VGA_LIBS = $(foreach x,$(LIBC_VGA_ARTIFACTS),$($(x)))
+LIBC_VGA_SRCS = $(foreach x,$(LIBC_VGA_ARTIFACTS),$($(x)_SRCS))
+LIBC_VGA_HDRS = $(foreach x,$(LIBC_VGA_ARTIFACTS),$($(x)_HDRS))
+LIBC_VGA_BINS = $(foreach x,$(LIBC_VGA_ARTIFACTS),$($(x)_BINS))
+LIBC_VGA_CHECKS = $(foreach x,$(LIBC_VGA_ARTIFACTS),$($(x)_CHECKS))
+LIBC_VGA_OBJS = $(foreach x,$(LIBC_VGA_ARTIFACTS),$($(x)_OBJS))
+LIBC_VGA_TESTS = $(foreach x,$(LIBC_VGA_ARTIFACTS),$($(x)_TESTS))
+$(LIBC_VGA_OBJS): $(BUILD_FILES) libc/vga/vga.mk
+
+.PHONY: o/$(MODE)/libc/vga
+o/$(MODE)/libc/vga: $(LIBC_VGA_CHECKS)

libc/vga/writev-vga.c

@@ -0,0 +1,129 @@
+/*-*- 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.h"
+#include "libc/runtime/pc.internal.h"
+#include "libc/str/str.h"
+
+#define CRTPORT 0x3d4
+#define WIDTH 80
+
+typedef struct {
+  char ch;
+  uint8_t attr;
+} char_cell_t;
+
+typedef char_cell_t char_row_t[WIDTH];
+
+const char vga_console[0];
+
+static unsigned short height = 25, curr_row = 12, curr_col = 0;
+static uint8_t curr_attr = 0x07;
+
+static void scroll(void) {
+  unsigned j;
+  uint8_t attr = curr_attr;
+  char_row_t * const vid_buf = (char_row_t *)(BANE + 0xb8000ull);
+  memmove(vid_buf, vid_buf + 1, (height - 1) * sizeof(char_row_t));
+  for (j = 0; j < WIDTH; ++j)
+    vid_buf[height - 1][j] = (char_cell_t){ ' ', attr };
+}
+
+static void may_scroll(void) {
+  if (curr_col >= WIDTH) {
+    curr_col = 0;
+    scroll();
+  }
+}
+
+static void updatexy_vga(void) {
+  unsigned short pos = curr_row * WIDTH + curr_col;
+  outb(CRTPORT, 0x0e);
+  outb(CRTPORT + 1, (unsigned char)(pos >> 8));
+  outb(CRTPORT, 0x0f);
+  outb(CRTPORT + 1, (unsigned char)pos);
+}
+
+static void writec_vga(char c) {
+  /* TODO: ensure screen in a known mode (text or graphics), at rlinit time */
+  /* TODO: use our own font, rather than rely on BIOS's CP437 font */
+  /* TODO: handle UTF-8 multi-bytes */
+  /* TODO: handle VT102 escape sequences */
+  /* TODO: maybe make BEL (\a) character code emit an alarm of some sort */
+  char_row_t * const vid_buf = (char_row_t *)(BANE + 0xb8000ull);
+  uint8_t attr = curr_attr;
+  unsigned short col;
+  switch (c) {
+    case '\b':
+      if (curr_col) {
+        col = curr_col - 1;
+        vid_buf[curr_row][col] = (char_cell_t){ ' ', attr };
+        curr_col = col;
+      }
+      break;
+    case '\t':
+      col = curr_col;
+      do {
+        vid_buf[curr_row][col] = (char_cell_t){ ' ', attr };
+        ++col;
+      } while (col % 8 != 0);
+      curr_col = col;
+      may_scroll();
+      break;
+    case '\r':
+      curr_col = 0;
+      break;
+    case '\n':
+      curr_col = 0;
+      if (curr_row < height - 1)
+        ++curr_row;
+      else
+        scroll();
+      break;
+    default:
+      col = curr_col;
+      vid_buf[curr_row][col] = (char_cell_t){ c, attr };
+      curr_col = col + 1;
+      may_scroll();
+  }
+}
+
+ssize_t sys_writev_vga(struct Fd *fd, const struct iovec *iov, int iovlen) {
+  char_row_t * const vid_buf = (char_row_t *)(BANE + 0xb8000ull);
+  size_t i, j, wrote = 0;
+  for (i = 0; i < iovlen; ++i) {
+    const char *input = (const char *)iov[i].iov_base;
+    for (j = 0; j < iov[i].iov_len; ++j) {
+      writec_vga(input[j]);
+      ++wrote;
+    }
+  }
+  updatexy_vga();
+  return wrote;
+}