Samsung YP-P10 Bedienungsanleitung PDF herunterladen (Seite 171)

100

101

S3C2440A RISC MICROPROCESSOR THUMB INSTRUCTION SET

4-23

OPERATION

These instructions transfer byte or word values between registers and memory using an immediate 5 or 7-bit offset.

The THUMB assembler syntax is shown in Table 4-10.

Table 4-10. Summary of Format 9 Instructions

L B THUMB assembler ARM equivalent Description

0 0 STR Rd, [Rb, #Imm] STR Rd, [Rb, #Imm] Calculate the target address by adding

together the value in Rb and Imm. Store

the contents of Rd at the address.

1 0 LDR Rd, [Rb, #Imm] LDR Rd, [Rb, #Imm] Calculate the source address by adding

together the value in Rb and Imm. Load

Rd from the address.

0 1 STRB Rd, [Rb, #Imm] STRB Rd, [Rb, #Imm] Calculate the target address by adding

together the value in Rb and Imm. Store

the byte value in Rd at the address.

1 1 LDRB Rd, [Rb, #Imm] LDRB Rd, [Rb, #Imm] Calculate source address by adding

together the value in Rb and Imm. Load

the byte value at the address into Rd.

NOTE: For word accesses (B = 0), the value specified by #Imm is a full 7-bit address, but must be word-aligned

(ie with bits 1:0 set to 0), since the assembler places #Imm >> 2 in the Offset5 field.

INSTRUCTION CYCLE TIMES

All instructions in this format have an equivalent ARM instruction as shown in Table 4-10. The instruction cycle times

for the THUMB instruction are identical to that of the equivalent ARM instruction.

EXAMPLES

LDR R2, [R5,#116] ; Load into R2 the word found at the address formed by

adding 116 to R5.Note that the THUMB opcode will

contain 29 as the Offset5 value.

STRB R1, [R0,#13] ; Store the lower 8 bits of R1 at the address formed by

adding 13 to R0.Note that the THUMB opcode will

contain 13 as the Offset5 value.

1 2 ... 166 167 168 169 170 171 172 173 174 175 176 ... 595 596

Kommentare zu diesen Handbüchern

Keine Kommentare

Samsung YP-P10 Bedienungsanleitung Seite 171

Kommentare zu diesen Handbüchern

Verwandte Produkte und Handbücher für MP3 / MP4-Player Samsung YP-P10