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Add x86_64-linux-gnu emulator

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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
This commit is contained in:
Justine Tunney 2020-08-25 04:23:25 -07:00
parent 467504308a
commit f4f4caab0e
1052 changed files with 65667 additions and 7825 deletions
Download patch file Download diff file Expand all files Collapse all files

53
libc/fmt/palandprintf.c
View file

@ -37,6 +37,7 @@
└─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/bits.h"
#include "libc/bits/weaken.h"
#include "libc/conv/conv.h"
#include "libc/escape/escape.h"
#include "libc/fmt/fmt.h"
@ -47,10 +48,12 @@
#include "libc/str/str.h"
#include "libc/sysv/errfuns.h"
static unsigned ppatoi(const char **str) {
unsigned i;
i = 0;
while (isdigit(**str)) i = i * 10u + (unsigned)(*((*str)++) - '0');
static int ppatoi(const char **str) {
int i;
for (i = 0; '0' <= **str && **str <= '9'; ++*str) {
i *= 10;
i += **str - '0';
}
return i;
}
@ -104,9 +107,14 @@ static unsigned ppatoi(const char **str) {
* @see printf() for wordier documentation
*/
hidden int palandprintf(void *fn, void *arg, const char *format, va_list va) {
void *p;
char qchar;
long double ldbl;
wchar_t charbuf[3];
const char *alphabet;
int (*out)(int, void *);
unsigned flags, width, precision;
int lasterr;
unsigned char signbit, log2base;
int w, rc, flags, width, lasterr, precision;
lasterr = errno;
out = fn ? fn : (int (*)(int, void *))missingno;
@ -161,7 +169,7 @@ hidden int palandprintf(void *fn, void *arg, const char *format, va_list va) {
if (isdigit(*format)) {
width = ppatoi(&format);
} else if (*format == '*') {
const int w = va_arg(va, int);
w = va_arg(va, int);
if (w < 0) {
flags |= FLAGS_LEFT; /* reverse padding */
width = -w;
@ -179,14 +187,16 @@ hidden int palandprintf(void *fn, void *arg, const char *format, va_list va) {
if (isdigit(*format)) {
precision = ppatoi(&format);
} else if (*format == '*') {
const int prec = (int)va_arg(va, int);
precision = prec > 0 ? prec : 0;
precision = va_arg(va, int);
format++;
}
}
if (precision < 0) {
precision = 0;
}
/* evaluate length field */
unsigned char signbit = 31;
signbit = 31;
switch (*format) {
case 'j': /* intmax_t */
format++;
@ -196,8 +206,8 @@ hidden int palandprintf(void *fn, void *arg, const char *format, va_list va) {
if (format[1] == 'l') format++;
/* fallthrough */
case 't': /* ptrdiff_t */
case 'Z': /* size_t */
case 'z': /* size_t */
case 'Z': /* size_t */
case 'L': /* long double */
format++;
signbit = 63;
@ -216,12 +226,9 @@ hidden int palandprintf(void *fn, void *arg, const char *format, va_list va) {
}
/* evaluate specifier */
void *p;
const char *alphabet = "0123456789abcdef";
unsigned log2base = 0;
wchar_t charbuf[3];
int rc;
char qchar = '"';
alphabet = "0123456789abcdef";
log2base = 0;
qchar = '"';
switch (*format++) {
case 'p':
flags |= FLAGS_ZEROPAD;
@ -256,23 +263,21 @@ hidden int palandprintf(void *fn, void *arg, const char *format, va_list va) {
}
case 'f':
case 'F': {
long double value;
case 'F':
if (signbit == 63) {
value = va_arg(va, long double);
ldbl = va_arg(va, long double);
} else {
value = va_arg(va, double);
ldbl = va_arg(va, double);
}
if (weaken(ftoa)(out, arg, value, precision, width, flags) == -1) {
if (weaken(ftoa)(out, arg, ldbl, precision, width, flags) == -1) {
return -1;
}
break;
}
case 'c':
qchar = '\'';
p = charbuf;
charbuf[0] = (wchar_t)va_arg(va, int); /* @assume little endian */
charbuf[0] = va_arg(va, int);
charbuf[1] = L'\0';
goto showstr;