Archival checkin (semi-working code).

mach/powerpc/libem/csb.s

@@ -0,0 +1,39 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+#include "powerpc.h"
+	
+.sect .text
+
+! this is not a subroutine, but just a
+! piece of code that computes the jump-
+! address and jumps to it.
+! traps if resulting address is zero
+!
+! On entry: r3 = address of CSB table
+!           r4 = value
+
+.define .csb
+.csb:
+	lwz r5, 0(r3)            ! load default
+	mtspr ctr, r5
+	
+	lwz r6, 4(r3)            ! fetch count
+	
+1:
+	or. r6, r6, r6           ! test count
+	bcctr IFTRUE, EQ, 0      ! exit if zero
+	addi r6, r6, -1          ! otherwise decrement
+	
+	lwzu r7, 8(r3)           ! fetch target index, increment pointer
+	cmp cr0, 0, r4, r7       ! compare with value
+	bc IFFALSE, EQ, 1b       ! if not equal, go again
+	
+	lwz r7, 4(r3)            ! fetch target address
+	mtspr ctr, r7
+	
+	or. r7, r7, r7           ! test it
+	bcctr IFFALSE, EQ, 0     ! jump to target if non-zero
+	b .trap_ecase            ! otherwise trap