R01UH0822EJ0100 Rev.1.00
Page 55 of 1041
Jul 31, 2019
RX13T Group
2. CPU
2.4
Data Types
The RX CPU can handle four types of data: integer, floating-point, bit, and string.
For details, refer to RX Family User's Manual: Software.
2.5
Endian
For the RX CPU, instructions are little endian, but the data arrangement is selectable as little or big endian.
2.5.1
Switching the Endian
As arrangements of bytes, this MCU supports both big endian, where the higher-order byte (MSB) is at location 0, and
little endian, where the lower-order byte (LSB) is at location 0.
For details on the endian setting, refer to
Operations for access differ according to the endian setting and, depending on the instruction, whether 8-, 16- or 32-bit
access has been selected. Operations for access in the various possible cases are described in
In the tables,
LL indicates bits D7 to D0 of the general-purpose register,
LH indicates bits D15 to D8 of the general-purpose register,
HL indicates bits D23 to D16 of the general-purpose register, and
HH indicates bits D31 to D24 of the general-purpose register.
D31 to D24
D23 to D16
D15 to D8
D7 to D0
General purpose register: Rm
HH
HL
LH
LL
Table 2.1
32-Bit Read Operations when Little Endian has been Selected
Operation
Address of src
Reading a 32-bit unit
from address 0
Reading a 32-bit unit
from address 1
Reading a 32-bit unit
from address 2
Reading a 32-bit unit
from address 3
Reading a 32-bit unit
from address 4
Address 0
Transfer to LL
—
—
—
—
Address 1
Transfer to LH
Transfer to LL
—
—
—
Address 2
Transfer to HL
Transfer to LH
Transfer to LL
—
—
Address 3
Transfer to HH
Transfer to HL
Transfer to LH
Transfer to LL
—
Address 4
—
Transfer to HH
Transfer to HL
Transfer to LH
Transfer to LL
Address 5
—
—
Transfer to HH
Transfer to HL
Transfer to LH
Address 6
—
—
—
Transfer to HH
Transfer to HL
Address 7
—
—
—
—
Transfer to HH
Table 2.2
32-Bit Read Operations when Big Endian has been Selected
Operation
Address of src
Reading a 32-bit unit
from address 0
Reading a 32-bit unit
from address 1
Reading a 32-bit unit
from address 2
Reading a 32-bit unit
from address 3
Reading a 32-bit unit
from address 4
Address 0
Transfer to HH
—
—
—
—
Address 1
Transfer to HL
Transfer to HH
—
—
—
Address 2
Transfer to LH
Transfer to HL
Transfer to HH
—
—
Address 3
Transfer to LL
Transfer to LH
Transfer to HL
Transfer to HH
—
Address 4
—
Transfer to LL
Transfer to LH
Transfer to HL
Transfer to HH
Address 5
—
—
Transfer to LL
Transfer to LH
Transfer to HL
Address 6
—
—
—
Transfer to LL
Transfer to LH
Address 7
—
—
—
—
Transfer to LL