1 2 #include <stdio.h> 3 #include <config.h> 4 5 static 6 int try_mtocrf ( int x ) 7 { 8 int base = 0x31415927; 9 int res; 10 #ifdef HAVE_AS_PPC_MFTOCRF 11 /* pre-set CR */ 12 __asm__ __volatile__( 13 "mtcr %0" 14 : /*w*/ : /*r*/ "b"(base) : /*trash*/"cc" ); 15 16 /* do it */ 17 __asm__ __volatile__( 18 "mtocrf 4, %0" 19 : /*w*/ : /*r*/ "b"(x) : /*trash*/"cc" ); 20 21 /* get CR */ 22 __asm__ __volatile__( 23 "mfcr %0" 24 : /*w*/"=b"(res) : /*r*/ ); 25 #else 26 res = 42; 27 #endif 28 return res; 29 } 30 31 static 32 int try_mfocrf ( int x ) 33 { 34 int res; 35 #ifdef HAVE_AS_PPC_MFTOCRF 36 /* CR = x */ 37 __asm__ __volatile__( 38 "mtcr %0" 39 : /*w*/ : /*r*/ "b"(x) : /*trash*/"cc" ); 40 41 /* do it */ 42 __asm__ __volatile__( 43 "li %0,0\n\t" 44 "mfocrf %0,64" 45 : /*w*/"=b"(res) : /*r*/ ); 46 #else 47 res = 42; 48 #endif 49 return res; 50 } 51 52 /* This is a bit of a kludge since mfocrf reads the spec'd CR field, 53 but the remaining returned bits are undefined. It seems like on 54 MPC7447A (Apple Mac Mini) mfocrf just reads the entire CR, which is 55 an acceptable implementation, but is not necessarily what other 56 implementations are going to do. */ 57 58 int main ( void ) 59 { 60 int i, j; 61 for (i = 0; i < 32; i++) { 62 printf("0x%08x\n", try_mtocrf( 1<<i )); 63 } 64 printf("\n"); 65 j = 1; 66 for (i = 0; i < 32; i++) { 67 printf("0x%08x\n", try_mfocrf( j )); 68 j *= 3; 69 } 70 71 return 0; 72 } 73
