gem5-endian-test.c

/*
 * Compile as follows:
 * 	gcc -O0 -nostdlib -static gem5-endian-test.c
 */

#ifndef __powerpc64__
#error "unsupported architecture"
#endif

#define MSG	"Hello world\n"
#define MSG_LEN	12

void _start()
{
	const char *msg = MSG;
	volatile register unsigned long gpr0 asm("r0");
	volatile register unsigned long gpr3 asm("r3");
	volatile register unsigned long gpr4 asm("r4");
	volatile register unsigned long gpr5 asm("r5");
	volatile register unsigned long gpr14 asm("r14");
	volatile register unsigned long gpr15 asm("r15");

	asm volatile("oris	%0, %0, 0xdead" : "=r"(gpr14) : "r"(gpr14));
	asm volatile("ori	%0, %0, 0xbeef" : "=r"(gpr14) : "r"(gpr14));
	asm volatile("sldi	%0, %0, 32" : "=r"(gpr14) : "r"(gpr14));
	asm volatile("oris	%0, %0, 0xdead" : "=r"(gpr14) : "r"(gpr14));
	asm volatile("ori	%0, %0, 0xbeef" : "=r"(gpr14) : "r"(gpr14));

	asm volatile("mtlr	%0" : : "r"(gpr14));
	asm volatile("mtcr	%0" : : "r"(gpr14));
	asm volatile("mtxer	%0" : : "r"(gpr14));
	asm volatile("mtctr	%0" : : "r"(gpr14));

	asm volatile("mr	%0, %1" : "=r"(gpr15) : "r"(msg));
	asm volatile("li	%0, 4"  : "=r"(gpr0));	/* sys_write */
	asm volatile("li	%0, 1"  : "=r"(gpr3));	/* STDOUT_FILENO */
	asm volatile("mr	%0, %1" : "=r"(gpr4) : "r"(gpr15));
	asm volatile("li	%0, %1" : "=r"(gpr5) : "i"(MSG_LEN));
	asm volatile("sc");

	asm volatile("std	%0, -8(1)" : : "r"(gpr14));

	/* fake endianness switch */
	asm volatile(".long	0x14000000");

	/* asm volatile("li	%0, 4"  : "=r"(gpr0)); */
	asm volatile(".long 0x04000038");
	/* asm volatile("li	%0, 1"  : "=r"(gpr3)); */
	asm volatile(".long 0x01006038");
	/* asm volatile("mr	%0, %1" : "=r"(gpr4) : "r"(gpr15)); */
	asm volatile(".long 0x787be47d");
	/* asm volatile("li	%0, %1" : "=r"(gpr5) : "i"(MSG_LEN)); */
	asm volatile(".long 0x0c00a038");
	/* asm volatile("sc"); */
	asm volatile(".long 0x02000044");

	/* asm volatile("ld	%0, -8(1)" : "=r"(gpr14)); */
	asm volatile(".long	0xf8ffc1e9");

	/* asm volatile("li	%0, 1" : "=r"(gpr0)); */
	asm volatile(".long	0x01000038");
	/* asm volatile("li	%0, 0" : "=r"(gpr3)); */
	asm volatile(".long	0x00006038");
	/* asm volatile("sc"); */
	asm volatile(".long	0x02000044");
}