Cần giúp đỡ

[haibang]

Ai rành về C, giải thích hộ mình đoạn code này, hoặc chuyền no sang ASM càng tốt, vì mình kô biết lập trình C

#include <REG51.H>
#define DISPL 80
#define MESS 984 // 984 bytes
#define DATAP P1

void DISP_SHOW();
void DISP_LOAD_BYTE(unsigned char A, unsigned char D);
void DISP_LOAD_BLOCK(unsigned char bf, unsigned char bt);
void DISP_LSHIFT(unsigned char DATA);
void DEL(int x);

code at 0x300 char MESSAGE[MESS]={
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0x7E,0xFF,0x81,0x81,0xC3,0x42,0x00,
0x00,0x7E,0xFF,0x81,0x81,0xFF,0x7E,0x00,
0x00,0xFF,0xFF,0x0E,0x70,0xFF,0xFF,0x00,
0x00,0x7E,0xFF,0x81,0xB1,0xF3,0x72,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0x03,0x03,0xFF,0xFF,0x03,0x03,0x00,
0x00,0x0F,0x1F,0xF0,0xF0,0x1F,0x0F,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0x03,0x03,0xFF,0xFF,0x03,0x03,0x00,
0x00,0xFF,0xFF,0x0E,0x70,0xFF,0xFF,0x00,
0x00,0xFF,0xFF,0x10,0x10,0xFF,0xFF,0x00,
0x00,0xFF,0xFF,0x10,0x10,0xFF,0xFF,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0xFE,0xFF,0x07,0x18,0x07,0xFF,0xFE,0x00,
0x00,0x03,0x03,0xFF,0xFF,0x03,0x03,0x00,
0x00,0x1F,0x7F,0xC0,0xC0,0x7F,0x1F,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0xFF,0xFF,0x80,0x80,0xC0,0xC0,0x00,
0x00,0xFC,0xFE,0x23,0x23,0xFE,0xFC,0x00,
0x00,0xFF,0xFF,0x11,0x11,0x1F,0x0E,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0x03,0x03,0xFF,0xFF,0x03,0x03,0x00,
0x00,0xFF,0xFF,0x31,0x71,0xDF,0x8E,0x00,
0x00,0xFF,0xFF,0x00,
0x00,0xFF,0xFF,0x0E,0x70,0xFF,0xFF,0x00,
0x00,0xFF,0xFF,0x10,0x10,0xFF,0xFF,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0x7E,0xFF,0x81,0x81,0xC3,0x42,0x00,
0x00,0xFF,0xFF,0x10,0x10,0xFF,0xFF,0x00,
0x00,0x7F,0xFF,0x80,0x80,0xFF,0x7F,0x00,
0x00,0x0F,0x1F,0xF0,0xF0,0x1F,0x0F,0x00,
0x00,0xFF,0xFF,0x99,0x99,0xC3,0xC3,0x00,
0x00,0xFF,0xFF,0x0E,0x70,0xFF,0xFF,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0x03,0x03,0xFF,0xFF,0x03,0x03,0x00,
0x00,0xFF,0xFF,0x10,0x10,0xFF,0xFF,0x00,
0x00,0xFF,0xFF,0x00,
0x00,0xFF,0xFF,0x99,0x99,0xC3,0xC3,0x00,
0x00,0x03,0x03,0xFF,0xFF,0x03,0x03,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0xFF,0xFF,0x3C,0x66,0xC3,0x81,0x00,
0x00,0xFF,0xFF,0x99,0x99,0xC3,0xC3,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x3F,0xFF,0xC0,0x30,0xC0,0xFF,0x3F,0x00,
0x00,0xFF,0xFF,0x99,0x99,0xC3,0xC3,0x00,
0x00,0xFF,0xFF,0x89,0x89,0xFF,0x76,0x00,
0x00,0x46,0xCF,0x99,0x99,0xFB,0x72,0x00,
0x00,0xFF,0xFF,0x00,
0x00,0x03,0x03,0xFF,0xFF,0x03,0x03,0x00,
0x00,0xFF,0xFF,0x99,0x99,0xC3,0xC3,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0x7E,0xFF,0x81,0xB1,0xF3,0x72,0x00,
0x00,0xFF,0xFF,0x00,
0x00,0xFC,0xFE,0x23,0x23,0xFE,0xFC,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0x7E,0xFF,0x81,0x81,0xC3,0x42,0x00,
0x00,0x7E,0xFF,0x81,0x81,0xFF,0x7E,0x00,
0x00,0xFF,0xFF,0x0E,0x70,0xFF,0xFF,0x00,
0x00,0x7E,0xFF,0x81,0xB1,0xF3,0x72,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0xFF,0xFF,0x11,0x11,0x1F,0x0E,0x00,
0x00,0xFF,0xFF,0x10,0x10,0xFF,0xFF,0x00,
0x00,0xFC,0xFE,0x23,0x23,0xFE,0xFC,0x00,
0x00,0xFF,0xFF,0x0E,0x70,0xFF,0xFF,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0xFE,0xFF,0x07,0x18,0x07,0xFF,0xFE,0x00,
0x00,0xFF,0xFF,0x99,0x99,0xC3,0xC3,0x00,
0xFE,0xFF,0x07,0x18,0x07,0xFF,0xFE,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0xFF,0xFF,0x81,0x81,0x7E,0x3C,0x00,
0x00,0xFF,0xFF,0x99,0x99,0xC3,0xC3,0x00,
0x00,0x46,0xCF,0x99,0x99,0xFB,0x72,0x00,
0x00,0xFF,0xFF,0x00,
0x00,0x7E,0xFF,0x81,0xB1,0xF3,0x72,0x00,
0x00,0xFF,0xFF,0x0E,0x70,0xFF,0xFF,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0xFF,0xFF,0x89,0x89,0xFF,0x76,0x00,
0x00,0x0F,0x1F,0xF0,0xF0,0x1F,0x0F,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

0x00,0x03,0x03,0xFF,0xFF,0x03,0x03,0x00,
0x00,0xFF,0xFF,0x10,0x10,0xFF,0xFF,0x00,
0x00,0x7F,0xFF,0x80,0x80,0xFF,0x7F,0x00,
0x00,0x7E,0xFF,0x81,0x81,0xFF,0x7E,0x00,
0x00,0xFF,0xFF,0x0E,0x70,0xFF,0xFF,0x00,
0x00,0x7E,0xFF,0x81,0xB1,0xF3,0x72,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
};
unsigned char MEMORY[DISPL]={
0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0};

void main (void) {
unsigned int N=0;
P1=0;
P3=255;
N=0;
DISP_LOAD_BLOCK(0, DISPL-1);
while(1){
while(P3_7);
while(!P3_7);
DISP_SHOW();
DISP_LSHIFT(MESSAGE[N]);
N++;
N=N%MESS;
}
}

void DISP_LOAD_BYTE(unsigned char A, unsigned char D)
{
MEMORY[A]=D;
}

void DISP_LOAD_BLOCK(unsigned char bf, unsigned char bt)
{
int I;
for(I-bf;I<bt;I++)
MEMORY[I]= MESSAGE[I];
}
void DISP_SHOW()
{
int I;
for(I-1;I<DISPL+1;I++){
DATAP= MEMORY[DISPL-I];
DEL(20);}
DATAP=0;
}

void DISP_LSHIFT(unsigned char DATA)
{
int I;
for(I=0;I<(DISPL-1);I++)
MEMORY[I]=MEMORY[I+1];
MEMORY[DISPL-1]=DATA;
}

void DEL(int x)
{
int I;
for(I=0;I<x;I++)
I=I+0;
}