Table of Contents
Advertisement
3 Data Formats
3.1 Data Formats Handled in Operations Between Registers
The S1C17 Core can handle 8-, 16-, and 24-bit data in register operations. In this manual, data sizes are expressed
as follows:
8-bit data
Byte, B, or b
16-bit data
Word, W, or w
24-bit data
Address data, A, a
Data sizes can be selected only in data transfer (load instruction) between one general-purpose register and another.
In an 8-bit data transfer with a general-purpose register as the destination, the data is sign- or zero-extended to 16
bits before being loaded into the register. Whether the data will be sign- or zero-extended is determined by the load
instruction used.
In a 16-bit or 8-bit data transfer using a general-purpose register as the source, the data to be transferred is stored in
the low-order 16 bits or the low-order 8 bits of the source register.
The data transfer sizes and types are described below.
3.1.1 Unsigned 8-Bit Transfer (Register → Register)
Example: ld.ub
%rd,%rs
%rs
%rd
Bits 23–8 in the destination register are set to 0x0000.
3.1.2 Signed 8-Bit Transfer (Register → Register)
Example: ld.b
%rd,%rs
%rs
%rd
Bits 15–8 in the destination register are sign-extended and bits 23–16 are set to 0x00.
S1C17 CORE MANUAL
(Rev. 1.2)
23
16
15
X
0
23
16 15
0
0
0
0
0
0
0
0
0
0
Figure 3.1.1.1 Unsigned 8-Bit Transfer (Register → Register)
23
16
15
X
0
23
16 15
0
0
0
0
0
0
0
0
S
S
Figure 3.1.2.1 Signed 8-Bit Transfer (Register → Register)
Seiko Epson Corporation
8
7
X
Byte
8
7
0
0
0
0
0
0
Byte
8 7
X
S
Byte
8
7
S
S
S
S
S
S
S
Byte
3 DATA FORMATS
0
0
0
0
3-1
Advertisement
Table of Contents
