so a little fun project "frogA- frogger Android" is taking some little progress.
https://www.youtube.com/shorts/4FAhYn2c5oU
Orginal posting can be fount here: http://blog.darkstar.work/2012/05/flex-fast-lexical-analyzer-generator.html
Who remember flex: fast lexical analyzer generator?
Here is a short sample, I have written it under gnu linux and ported it to win32 using gnuwin32 flex and getoptwin:
We have this simple c modified code from stack overflow called funcptrtest.c:
include <stdio.h>
/* C code for program funcptrtest.c
=> https://pastebin.com/rUtXfgSG
*/
const int b = 23;
// A normal function with an int parameter and void return type
void fun(int a)
{
if (a < b)
printf("Value of a (%d) is lesser then value of b (%d)\n", a, b);
else if (a == b)
printf("Value of a (%d) is equal value of b (%d)\n", a, b);
else if (a > b)
printf("Value of a (%d) is greater than value of b (%d)\n", a, b);
}
// main => NO KNR style int main(argc, argv) int argc; char **argv
int main(int argc, char **argv)
{
int i = 0;
/* fun_ptr is a pointer to function fun()
void (*fun_ptr)(int) = &fun;
is equivalent of following two
void (*fun_ptr)(int);
fun_ptr = &fun;
*/
void (*fun_ptr)(int) = &fun;
// call once with static int
(*fun_ptr)(b);
// iterate through for loop
for (i = 1; i < 101; i+=11) {
// Invoking fun() using fun_ptr
(*fun_ptr)(i);
}
return 0;
}
We compile it now with gnu c compiler with gcc option -S and generate an assembler file:
gcc -S funcptrtest.c -o funcptrtest.asm
Result will be something like this:
.file "funcptrtest.c"
.text
.globl b
.section .rodata
.align 4
.type b, @object
.size b, 4
b:
.long 23
.align 8
.LC0:
.string "Value of a (%d) is lesser then value of b (%d)\n"
.align 8
.LC1:
.string "Value of a (%d) is equal value of b (%d)\n"
.align 8
.LC2:
.string "Value of a (%d) is greater than value of b (%d)\n"
.text
.globl fun
.type fun, @function
fun:
.LFB0:
.cfi_startproc
endbr64
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
movq %rsp, %rbp
.cfi_def_cfa_register 6
subq $16, %rsp
movl %edi, -4(%rbp)
movl $23, %eax
cmpl %eax, -4(%rbp)
jge .L2.L2:
movl $23, %eax
cmpl %eax, -4(%rbp)
jne .L4
movl $23, %edx
movl -4(%rbp), %eax
movl %eax, %esi
leaq .LC1(%rip), %rax
movq %rax, %rdi
movl $0, %eax
call printf@PLT
jmp .L5
.L2:
movl $23, %eax
cmpl %eax, -4(%rbp)
jne .L4
movl $23, %edx
movl -4(%rbp), %eax
movl %eax, %esi
leaq .LC1(%rip), %rax
movq %rax, %rdi
movl $0, %eax
call printf@PLT
.L2:
movl $23, %eax
cmpl %eax, -4(%rbp)
jne .L4
movl $23, %edx
movl -4(%rbp), %eax
movl %eax, %esi
leaq .LC1(%rip), %rax
movq %rax, %rdi
movl $0, %eax
call printf@PLT
jmp .L5
.L4:
movl $23, %eax
cmpl %eax, -4(%rbp)
jle .L5
movl $23, %edx
movl -4(%rbp), %eax
movl %eax, %esi
leaq .LC2(%rip), %rax
movq %rax, %rdi
movl $0, %eax
call printf@PLT
.L5:
nop
leave
.cfi_def_cfa 7, 8
ret
.cfi_endproc
.LFE0:
.size fun, .-fun
.globl main
.type main, @function
main:
.LFB1:
.cfi_startproc
endbr64
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
movq %rsp, %rbp
.cfi_def_cfa_register 6
subq $32, %rsp
movl %edi, -20(%rbp)
movq %rsi, -32(%rbp)
movl $0, -12(%rbp)
leaq fun(%rip), %rax
movq %rax, -8(%rbp)
movl $23, %edx
movq -8(%rbp), %rax
movl %edx, %edi
call *%rax
movl $1, -12(%rbp)
jmp .L7
.L8:
movl -12(%rbp), %eax
movq -8(%rbp), %rdx
movl %eax, %edi
call *%rdx
addl $11, -12(%rbp)
.L7:
cmpl $100, -12(%rbp)
jle .L8
movl $0, %eax
leave
.cfi_def_cfa 7, 8
ret
.cfi_endproc
.LFE1:
.size main, .-main
.ident "GCC: (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0"
.section .note.GNU-stack,"",@progbits
.section .note.gnu.property,"a"
.align 8
.long 1f - 0f
.long 4f - 1f
.long 5
0:
.string "GNU"
1:
.align 8
.long 0xc0000002
.long 3f - 2f
2:
.long 0x3
3:
.align 8
4:
Lets look, if a simple loop is faster than a function pointer delegate call:
/* program looptest.c */
include <stdio.h>
const int b = 23;
// main
int main(int argc, char **argv)
{
int i = 0;
int a = 23;
/*
if (a < b)
printf("Value of a (%d) is lesser then value of b (%d)\n", a, b);
else if (a == b)
printf("Value of a (%d) is equal value of b (%d)\n", a, b);
else if (a > b)
printf("Value of a (%d) is greater than value of b (%d)\n", a, b);
*/
// iterate through for loop
for (i = 1; i < 4194304; i+=11) {
a = i;
if (a < b)
printf("Value of a (%d) is lesser then value of b (%d)\n", a, b);
else if (a == b)
printf("Value of a (%d) is equal value of b (%d)\n", a, b);
else if (a > b)
printf("Value of a (%d) is greater than value of b (%d)\n", a, b);
}
return 0;
}
/* program funcptrtest.c */
include <stdio.h>
const int b = 23;
// A normal function with an int parameter and void return type
void fun(int a)
{
if (a < b)
printf("Value of a (%d) is lesser then value of b (%d)\n", a, b);
else if (a == b)
printf("Value of a (%d) is equal value of b (%d)\n", a, b);
else if (a > b)
printf("Value of a (%d) is greater than value of b (%d)\n", a, b);
}
// main
int main(int argc, char **argv)
{
int i = 0;
/* fun_ptr is a pointer to function fun()
void (*fun_ptr)(int) = &fun;
is equivalent of following two
void (*fun_ptr)(int);
fun_ptr = &fun;
*/
void (*fun_ptr)(int) = &fun;
// call once with static int
// (*fun_ptr)(b);
// iterate through for loop
for (i = 1; i < 4194304; i+=11) {
// Invoking fun() using fun_ptr
(*fun_ptr)(i);
}
return 0;
}
Well, that's not so deterministic, of course our simple looptest.asm has a shorter assembler.
But execution time is not so huge difference, we have to simulate, that in many scenarios.
[To be continued ...]
Most complete Identity of a person is defined / determined by different public, restricted or private accessible spheres.
Attention:
This article isn't about daily standard electronic communications via network protocols (e.g. email services or shared network folders), neither about user authentication / authorization nor groupware.
It's about:
Implementing or consuming customizable reliable distributed services;
by choosing & implementing a programmable extensible scalable, easily portable, standardized inter-compatible fail-safe resilient communication middleware, that's financially essential for most critical business processes.
For what kind of companies is that useful, important or relevant?
It's relevant for all companies, that consume many crtical data from external partners / service providers;
then process received & own data inside different departments (maybe in different locations) with different areas of responsibility (e.g. fraud detection, critical real-time scaling of dynamic hardware (memory, harddisks and available CPUs, permanent risk adjustment and last but not least anonymized [General Data Protection Regulation] precise reporting for legal reasons);
finally and ultimately share processed data to maybe different external organisations with very deviating requirements, like government fraud reporting agency on one side and partners inside a foundation or joint umbrella organization however.
[ to be continued ... ]
-
I'm left liberal atheist, but I want to show thou, that I like some church music very much.