一个很简单的例子,打印256个字节
#include <Uefi.h>
#include <Library/UefiLib.h>
#include <Library/ShellCEntryLib.h>
extern EFI_BOOT_SERVICES *gBS;
extern EFI_SYSTEM_TABLE *gST;
extern EFI_RUNTIME_SERVICES *gRT;
static UINT32 next = 1;
/** Expands to an integer constant expression that is the maximum value
returned by the rand function.
**/
#define RAND_MAX 0x7fffffff
/** Compute a pseudo-random number.
*
* Compute x = (7^5 * x) mod (2^31 - 1)
* without overflowing 31 bits:
* (2^31 - 1) = 127773 * (7^5) + 2836
* From "Random number generators: good ones are hard to find",
* Park and Miller, Communications of the ACM, vol. 31, no. 10,
* October 1988, p. 1195.
**/
int
rand()
{
INT32 hi, lo, x;
/* Can't be initialized with 0, so use another value. */
if (next == 0)
next = 123459876;
hi = next / 127773;
lo = next % 127773;
x = 16807 * lo - 2836 * hi;
if (x < 0)
x += 0x7fffffff;
return ((next = x) % ((UINT32)RAND_MAX + 1));
}
void
srand(unsigned int seed)
{
next = (UINT32)seed;
}
int
EFIAPI
main (
IN int Argc,
IN CHAR16 **Argv
)
{
UINT32 Buffer[256];
UINT32 i;
UINT32 j;
srand(0);
for (i=0;i<256;i++)
{
Buffer[i]=(UINT8)(rand()%256);
}
Print(L" \\|");
for (i=0;i<16;i++)
{
Print(L" %2X|",i);
}
Print(L"\n");
for (j=0;j<16;j++)
{
Print(L"%2X| ",j);
for (i=0;i<16;i++)
{
Print(L"%2X ",Buffer[i*16+j]);
}
Print(L"\n");
}
return EFI_SUCCESS;
}
运行结果:
完整的程序
