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Section 2 CPU
Rev. 4.00 Sep. 14, 2005 Page 57 of 982
REJ09B0023-0400
DSP Addressing Operations: DSP addressing operations in the pipeline execution stage (EX),
including modulo addressing, are shown below.
if ( Operation is MOVX.W MOVY.W ) {
ABx=Ax; ABy=Ay;
/* memory access cycle uses ABx and ABy. The addresses to be used have not been updated */
/* Ax is one of R4,5 */
if ( DMX==0 || DMX==1 && DMY == 1 )} Ax=Ax+(+2 or R8[Ix] or +0);
/* Inc,Index,Not-Update */
else if (! not-update) Ax=modulo( Ax, (+2 or R8[Ix]) );
/* Ay is one of R6,7 */
if ( DMY==0 ) Ay=Ay+(+2 or R9[Iy] or +0); /* Inc,Index,Not-Update */
else if (! not-update) Ay=modulo( Ay, (+2 or R9[Iy]) );
}
else if ( Operation is MOVS.W or MOVS.L ) {
if ( Addressing is Nop, Inc, Add-index-reg ) {
MAB=As;
/* memory access cycle uses MAB. The address to be used has not been updated */
/* As is one of R2 to R5 */
As=As+(+2 or +4 or R8[Is] or +0); /* Inc,Index,Not-Update */
else { /* Decrement, Pre-update */
/* As is one of R2 to R5 */
As=As+(-2 or -4);
MAB=As;
/* memory access cycle uses MAB. The address to be used has been updated */
}
/* The value to be added to the address register depends on addressing operations.
For example, (+2 or R8[Ix] or +0) means that
+2 : if operation is increment
R8[Ix] : if operation is add-index-reg
+0 : if operation is not-update
*/
function modulo ( AddrReg, Index ) {
if ( AdrReg[15:0]==ME ) AdrReg[15:0]==MS;
else AdrReg=AdrReg+Index;
return AddrReg;
}