dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 73

• Manufacturer Part Number: dsp56800e
• Description: 16-bit Digital Signal Controller Core
• Manufacturer: Freescale Semiconductor, Inc

3.6
Addressing modes specify where the operands for an instruction can be found (in an immediate value, in a
register, or in memory) and provide the exact addresses of the operands. The DSP56800E instruction set
contains a full set of operand addressing modes, which are optimized for high-performance signal
processing as well as for efficient controller code. All address calculations are performed in the address
generation unit to minimize execution time.
The addressing modes are grouped into four categories:
These addressing modes are referred to extensively in Section 4.4.4, “Instruction Summary Tables,” on
page 4-20.
An effective address in an instruction specifies the addressing mode. In some addressing modes, the
effective address further specifies an address register that points to a location in memory, how the address
is calculated, and how the register is updated.
3.6.1
This section contains a series of tables that summarize all of the addressing modes in the DSP56800E. The
notation used in these tables to reference AGU registers is summarized in Table 3-8.
Table 3-9 on page 3-24 shows all accessible DSP56800E registers (register direct).
Table 3-10 on page 3-25 shows data and program memory accesses (address register indirect).
Table 3-11 on page 3-25 shows all immediate addressing modes.
Table 3-12 on page 3-26 shows all absolute addressing modes.
Freescale Semiconductor
Register Field
•
•
•
•
RRR
Register direct—directly references the registers on the chip as operands
Address register indirect—uses an address register as a pointer to reference a location in memory
as an operand
Immediate—operand is contained as a value within the instruction itself
Absolute—uses the address contained within the instruction itself to reference a location in memory
as an operand
Rn
Rk
Rj
Addressing Modes
Addressing Mode Summary
R0, R1, R2, R3
R0–R5, N, SP
R0–R3, N, SP
Registers
R0–R5, N
Table 3-8. Notation for AGU Registers
Data Types and Addressing Modes
Seven AGU address registers
Eight AGU address registers
Six AGU address registers (DSP56800 registers)
Four pointer registers available for addressing
Comments
Addressing Modes
3-23