beremiz

use pregenerated CRC32 lookup tables for retain on Win32 and GNU/Linux

2019-01-06, Andrey Skvortsov
68f4f2d4516b
use pregenerated CRC32 lookup tables for retain on Win32 and GNU/Linux

This code could be possible reused on low-end targets with limited RAM.

code to generate lookup table:
[---------------------------------------------------------------------]

/* CRC lookup table and initial state. */
uint32_t crc32_table[256];

/* Generate CRC32 lookup table. */
void GenerateCRC32Table(void)
{
unsigned int i, j;
/* Use CRC-32-IEEE 802.3 polynomial 0x04C11DB7 (bit reflected). */
uint32_t poly = 0xEDB88320;

for (i = 0; i <= 0xFF; i++)
{
uint32_t c = i;
for (j = 0 ; j < 8 ; j++)
c = (c & 1) ? (c >> 1 ) ^ poly : (c >> 1);
crc32_table[i] = c;
}
}

void main(void)
{
GenerateCRC32Table();
int j=0;
for(int i=0; i<256; i++) {
printf("0x%08X, ", crc32_table[i]);
if (++j >= 8) {
j = 0;
printf("\n");
}
}
}
[---------------------------------------------------------------------]
# the platform name (PyV8, smjs, Mozilla, IE6, Opera, Safari etc.)
platform = '' # to be updated by app, on compile
# a dictionary of module override names (platform-specific)
overrides = {} # to be updated by app, on compile
# the remote path for loading modules
loadpath = None
stacktrace = None
appname = None
def setloadpath(lp):
global loadpath
loadpath = lp
def setappname(an):
global appname
appname = an
def getloadpath():
return loadpath
def addoverride(module_name, path):
overrides[module_name] = path
def addstack(linedebug):
JS("""
if (pyjslib.bool((sys.stacktrace === null))) {
sys.stacktrace = new pyjslib.List([]);
}
sys.stacktrace.append(linedebug);
""")
def popstack():
JS("""
sys.stacktrace.pop()
""")
def printstack():
JS("""
var res = '';
var __l = sys.stacktrace.__iter__();
try {
while (true) {
var l = __l.next();
res += ( l + '\\n' ) ;
}
} catch (e) {
if (e != pyjslib.StopIteration) {
throw e;
}
}
return res;
""")