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https://github.com/jart/cosmopolitan.git
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f4f4caab0e
I wanted a tiny scriptable meltdown proof way to run userspace programs and visualize how program execution impacts memory. It helps to explain how things like Actually Portable Executable works. It can show you how the GCC generated code is going about manipulating matrices and more. I didn't feel fully comfortable with Qemu and Bochs because I'm not smart enough to understand them. I wanted something like gVisor but with much stronger levels of assurances. I wanted a single binary that'll run, on all major operating systems with an embedded GPL barrier ZIP filesystem that is tiny enough to transpile to JavaScript and run in browsers too. https://justine.storage.googleapis.com/emulator625.mp4
135 lines
6 KiB
C
135 lines
6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/math.h"
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#include "libc/runtime/gc.h"
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#include "libc/stdio/stdio.h"
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#include "libc/str/str.h"
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#include "libc/x/x.h"
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#include "third_party/dtoa/dtoa.h"
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const char kConfig[] = "\
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/* FPU Control Word (x87) Exception Masks\n\
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@see Intel Manual V1 §8.1.5\n\
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IM: Invalid Operation ───────────────┐\n\
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DM: Denormal Operand ───────────────┐│\n\
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ZM: Zero Divide ───────────────────┐││\n\
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OM: Overflow ─────────────────────┐│││\n\
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UM: Underflow ───────────────────┐││││\n\
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PM: Precision ──────────────────┐│││││\n\
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PC: Precision Control ────────┐ ││││││\n\
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{float,∅,double,long double} │ ││││││\n\
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RC: Rounding Control ───────┐ │ ││││││\n\
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{even, →-∞, →+∞, →0} │┌┤ ││││││\n\
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┌┤││ ││││││\n\
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d││││rr││││││*/\n\
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";
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const char kStatus[] = "\
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/* FPU Status Word (x87)\n\
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@see Intel Manual V1 §8.1.3\n\
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IE: Invalid Operation ────────────────┐\n\
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DE: Denormalized Operand ────────────┐│\n\
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ZE: Zero Divide ────────────────────┐││\n\
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OE: Overflow Flag ─────────────────┐│││\n\
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UE: Underflow Flag ───────────────┐││││\n\
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PE: Precision Flag ──────────────┐│││││\n\
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SF: Stack Fault ────────────────┐││││││\n\
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ES: Exception Summary Status ──┐│││││││\n\
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C0-3: Condition Codes ──┬────┐ ││││││││\n\
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TOP of Stack Pointer ─────┐ │ ││││││││\n\
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B: FPU Busy ───────────┐│ │ │ ││││││││\n\
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││┌┴┐┌┼┐││││││││\n\
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│↓│ │↓↓↓││││││││*/\n\
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";
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const char kRegister[] = "\
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/\t┌sign\n\
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/\t│ ┌exponent\n\
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/\t│ │ ┌intpart\n\
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/\t│ │ │ ┌fraction\n\
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/\t│ │ │ │\n\
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/\t│┌┴────────────┐│┌┴────────────────────────────────────────────────────────────┐\n";
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void PrintRegister(long double x) {
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char buf[32];
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uint16_t lo, hi;
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memcpy(buf, &x, sizeof(x));
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memcpy(&lo, &buf[0], sizeof(lo));
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memcpy(&hi, &buf[8], sizeof(hi));
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printf("/\t%016lb%064lb %s\n", hi, lo, g_fmt(buf, x));
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}
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int main(int argc, char *argv[]) {
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double d;
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unsigned short sw;
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long double st0, st1;
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#define ST0 1
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#define ST1 2
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d = 0;
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st0 = ST0;
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st1 = ST1;
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asm("fstl\t%1\n\t"
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"fstsw"
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: "=a"(sw), "=m"(d) /*, "+t"(st0), "+u"(st1) */);
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printf("\n%s%016b\n\n%s", kStatus, sw, kRegister);
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PrintRegister(st0);
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PrintRegister(st1);
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printf("/\t%-80s %s\n", "d", gc(xdtoa(d)));
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#if 0
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#define ST0 2e18L
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#define ST1 0.0000000000000123L
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st0 = ST0;
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st1 = ST1;
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asm("fldpi\n\t"
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"fadd\t%%st\n\t"
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"fxch\n2:\t"
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"fprem1\n\t"
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"fnstsw\n\t"
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"test\t$4,%%ah\n\t"
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"jnz\t2b\n\t"
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"fstp\t%%st(1)\n\t"
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"fsin\n\t"
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"fstsw"
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: "=a"(sw), "+t"(st0), "+u"(st1));
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printf("\n%s%016b\n\n%s", kStatus, sw, kRegister);
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PrintRegister(st0);
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PrintRegister(st1);
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#endif
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#if 0
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st0 = ST0;
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st1 = ST1;
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asm("fsin\n\t"
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"fstsw"
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: "=a"(sw), "+t"(st0), "+u"(st1));
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printf("\n%s%016b\n\n%s", kStatus, sw, kRegister);
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PrintRegister(st0);
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PrintRegister(st1);
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#endif
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#if 0
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printf("\n");
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PrintRegister(sinl(remainderl(2e40L, M_PI * 2)));
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#endif
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return 0;
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}
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