Multiply-Accumulate Register (Mac); Initial Values Of Cpu Registers - Renesas H8S Series Hardware Manual

Section 2 CPU
Bit Bit Name
0 C
2.4.5

Multiply-Accumulate Register (MAC)

This 64-bit register stores the results of multiply-and-accumulate operations. It consists of two 32-
bit registers denoted MACH and MACL. The lower 10 bits of MACH are valid; the upper bits are
a sign extension.
2.4.6

Initial Values of CPU Registers

Reset exception handling loads the CPU's program counter (PC) from the vector table, clears the
trace bit in EXR to 0, and sets the interrupt mask bits in CCR and EXR to 1. The other CCR bits
and the general registers are not initialized. In particular, the stack pointer (ER7) is not initialized.
The stack pointer should therefore be initialized by an MOV.L instruction executed immediately
after a reset.
Rev. 6.00 Mar 15, 2006 page 26 of 570
REJ09B0211-0600
Initial Value R/W
undefined R/W
Description
Carry Flag
Set to 1 when a carry occurs, and cleared to 0
otherwise. Used by:
•
Add instructions, to indicate a carry
•
Subtract instructions, to indicate a borrow
•
Shift and rotate instructions, to indicate a carry
The carry flag is also used as a bit accumulator by
bit manipulation instructions.