MSC8144E Reference Manual, Rev. 3
2-6
Freescale
Semiconductor
SC3400 Core Overview
The two AAUs are identical. Each contains a 32-bit full adder called an offset adder and a 32-bit
full adder called a modulo adder. The offset adder performs the following operations:
Add or subtract an AGU registers or PC to/from an AGU register
Add or subtract an immediate value to/from an AGU register
Compare to or test an AGU register
Logical and arithmetic shift operations on AGU registers
Sign or zero-extend an AGU register
Add with reverse carry
The offset values added in this adder are pre-shifted by 1, 2, or 3, according to the access width.
In reverse-carry mode, the carry propagates in the opposite direction. The modulo adder adds the
summed result of the first full adder to a modulo value, M or minus M, where M is stored in the
selected modifier register. In modulo mode, the modulo comparator tests whether the result is
inside the buffer by comparing the results to the B register and chooses the correct result from
between the offset adder and the modulo adder.
2.1.2.1 Stack Pointer Registers
To facilitate use of a software stack, two special registers with special addressing modes are
assigned to the AGU: the Normal Mode Stack Pointer (NSP) and the Exception Mode Stack
Pointer (ESP). Both the ESP and the NSP are 32-bit read/write address registers with
predecrement and post-increment updates, as well as offset with immediate values to allow
random access to the software stack. Stack instructions use the ESP when the MSC8144E is in
the Exception mode of operation, which it enters when exceptions occur. The NSP is used in
Normal mode, while not servicing an exception. The two stack pointers make it easier to support
multitasking systems and optimizes stack usage for these systems.
2.1.2.2 Bit Mask Unit (BMU)
The BMU performs bit mask operations, such as setting, clearing, changing, or testing a
destination, according to an immediate mask operand. Data is loaded to the BMU over the data
memory buses Xa or Xb. The result is written back over the Xa data bus or Xb data bus to the
destinations in the next cycle. All bit mask instructions typically execute in two cycles and work
on 16-bit data. This data can be a memory location, or a portion (high or low) of a register. The
BMU supports a set of bit mask instructions that operate on:
All AGU pointers (R[0–15])
All Data ALU registers (D[0–15])
All control registers (EMR, VBA, SR, MCTL)
Memory locations
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...