Add pseudoteletypewriter to emulator

https://justine.storage.googleapis.com/emulator628.mp4

libc/runtime/construct.S

@@ -23,6 +23,11 @@
 .source	__FILE__
 
 /	Calls global initialization functions.
+/
+/	@param	r12 is argc
+/	@param	r13 is argv
+/	@param	r14 is environ
+/	@param	r15 is auxv
 _construct:
 	push	%rbp
 	mov	%rsp,%rbp

libc/runtime/cxaatexit.c

@@ -43,8 +43,8 @@ static struct CxaAtexitBlocks {
  *
  * Destructors are called in reverse order. They won't be called if the
  * program aborts or _exit() is called. Invocations of this function are
- * usually generated by the C++ compiler. Behavior is limitless if you
- * choose to link calloc() and free().
+ * usually generated by the C++ compiler. Behavior is limitless if some
+ * other module has linked calloc().
  *
  * @param fp is void(*)(T)
  * @param arg is passed to callback
@@ -78,8 +78,11 @@ int __cxa_atexit(void *fp, void *arg, void *pred) {
 /**
  * Triggers global destructors.
  *
+ * They're called in LIFO order. If a destructor adds more destructors,
+ * then those destructors will be called immediately following, before
+ * iteration continues.
+ *
  * @param pred can be null to match all
- * @note reentrant emptor
  */
 void __cxa_finalize(void *pred) {
   unsigned i;

libc/runtime/enableavx.greg.c

@@ -1,71 +0,0 @@
-/*-*- 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│
-╞══════════════════════════════════════════════════════════════════════════════╡
-│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
-│                                                                              │
-│ This program is free software; you can redistribute it and/or modify         │
-│ it under the terms of the GNU General Public License as published by         │
-│ the Free Software Foundation; version 2 of the License.                      │
-│                                                                              │
-│ This program is distributed in the hope that it will be useful, but          │
-│ WITHOUT ANY WARRANTY; without even the implied warranty of                   │
-│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU             │
-│ General Public License for more details.                                     │
-│                                                                              │
-│ You should have received a copy of the GNU General Public License            │
-│ along with this program; if not, write to the Free Software                  │
-│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
-│ 02110-1301 USA                                                               │
-╚─────────────────────────────────────────────────────────────────────────────*/
-#include "ape/lib/pc.h"
-#include "libc/dce.h"
-#include "libc/nexgen32e/nexgen32e.h"
-#include "libc/nt/struct/context.h"
-#include "libc/nt/thunk/msabi.h"
-
-#define kNtContextXstate 0x00100040
-#define kNtXstateAvx     2
-#define kNtXstateMaskAvx (1ull << kNtXstateAvx)
-
-static void EnableAvx(void) {
-  asm volatile("mov\t%%cr4,%%rax\n\t"
-               "or\t%0,%%rax\n\t"
-               "mov\t%%rax,%%cr4\n\t"
-               "xor\t%%ecx,%%ecx\n\t"
-               "xgetbv\n\t"
-               "or\t%1,%%eax\n\t"
-               "xsetbv"
-               : /* no outputs */
-               : "i"(CR4_OSXSAVE), "i"(XCR0_X87 | XCR0_SSE | XCR0_AVX)
-               : "rax", "rcx", "rdx", "memory", "cc");
-}
-
-static void EnableAvxOnWindows(void) {
-  /* typedef uint64_t (*getenabledxstatefeatures_f)(void) __msabi; */
-  /* typedef bool32 (*initializecontext_f)(void *buffer, uint32_t flags, */
-  /*                                       struct NtContext **out_context, */
-  /*                                       uint32_t *inout_buffersize) __msabi;
-   */
-  /* typedef bool32 (*getxstatefeaturesmask_f)(struct NtContext * context, */
-  /*                                           uint64_t * out_featuremask)
-   * __msabi; */
-  /* typedef bool32 (*setxstatefeaturesmask_f)(struct NtContext * context, */
-  /*                                           uint64_t featuremask) __msabi; */
-  /* getenabledxstatefeatures_f GetEnabledXStateFeatures; */
-  /* initializecontext_f InitializeContext; */
-  /* getxstatefeaturesmask_f GetXStateFeaturesMask; */
-  /* setxstatefeaturesmask_f SetXStateFeaturesMask; */
-}
-
-/**
- * Requests authorization from operating system to do 256-bit math.
- * @assume avx cpuid check performed by caller
- */
-int _init_enableavx(void) {
-  if (IsMetal()) {
-    EnableAvx();
-  } else if (IsWindows()) {
-    EnableAvxOnWindows();
-  }
-  return 0;
-}

libc/runtime/mmap.c

@@ -129,7 +129,7 @@ void *mmap(void *addr, size_t size, int prot, int flags, int fd, int64_t off) {
   if (!CANONICAL(addr)) return VIP(einval());
   if (!(!!(flags & MAP_ANONYMOUS) ^ (fd != -1))) return VIP(einval());
   if (!(!!(flags & MAP_PRIVATE) ^ !!(flags & MAP_SHARED))) return VIP(einval());
-  if (!(IsWindows() && fd != -1)) size = ROUNDUP(size, FRAMESIZE);
+  if (fd != -1) size = ROUNDUP(size, FRAMESIZE);
   if (flags & MAP_FIXED) {
     if (UntrackMemoryIntervals(addr, size) == -1) {
       return MAP_FAILED;

libc/runtime/runtime.mk

@@ -37,6 +37,7 @@ LIBC_RUNTIME_A_DIRECTDEPS =				\
 	LIBC_BITS					\
 	LIBC_CALLS					\
 	LIBC_CONV					\
+	LIBC_TINYMATH					\
 	LIBC_ELF					\
 	LIBC_FMT					\
 	LIBC_NEXGEN32E					\

libc/runtime/spawn.S

@@ -22,6 +22,11 @@
 #include "libc/macros.h"
 
 /	Self-bootstraps process upon existence before calling main.
+/
+/	@param	r12 is argc
+/	@param	r13 is argv
+/	@param	r14 is environ
+/	@param	r15 is auxv
 _spawn:	push	%rbp
 	mov	%rsp,%rbp