2. Programming Model
Rev.1.00 Jan. 10, 2008 Page 40 of 1658
REJ09B0261-0100
2.4
Data Formats in Registers
Register operands are always longwords (32 bits). When a memory operand is only a byte (8 bits)
or a word (16 bits), it is sign-extended into a longword when loaded into a register.
31
S
S
S
0
6
7
6
7
0
31
S
S
S
0
14
15
14
15
0
Figure 2.6 Formats of Byte Data and Word Data in Register
2.5
Data Formats in Memory
Memory data formats are classified into bytes, words, and longwords. Memory can be accessed in
an 8-bit byte, 16-bit word, or 32-bit longword form. A memory operand less than 32 bits in length
is sign-extended before being loaded into a register.
A word operand must be accessed starting from a word boundary (even address of a 2-byte unit:
address 2n), and a longword operand starting from a longword boundary (even address of a 4-byte
unit: address 4n). An address error will result if this rule is not observed. A byte operand can be
accessed from any address.
Big endian or little endian byte order can be selected for the data format. The endian should be set
with the external pin after a power-on reset. The endian cannot be changed dynamically. Bit
positions are numbered left to right from most-significant to least-significant. Thus, in a 32-bit
longword, the leftmost bit, bit 31, is the most significant bit and the rightmost bit, bit 0, is the least
significant bit.
The data format in memory is shown in figure 2.7.
Summary of Contents for SH7781
Page 4: ...Rev 1 00 Jan 10 2008 Page iv of xxx REJ09B0261 0100 ...
Page 74: ...2 Programming Model Rev 1 00 Jan 10 2008 Page 44 of 1658 REJ09B0261 0100 ...
Page 272: ...8 Caches Rev 1 00 Jan 10 2008 Page 242 of 1658 REJ09B0261 0100 ...
Page 376: ...10 Interrupt Controller INTC Rev 1 00 Jan 10 2008 Page 346 of 1658 REJ09B0261 0100 ...
Page 694: ...13 PCI Controller PCIC Rev 1 00 Jan 10 2008 Page 664 of 1658 REJ09B0261 0100 ...
Page 762: ...14 Direct Memory Access Controller DMAC Rev 1 00 Jan 10 2008 Page 732 of 1658 REJ09B0261 0100 ...
Page 788: ...15 Clock Pulse Generator CPG Rev 1 00 Jan 10 2008 Page 758 of 1658 REJ09B0261 0100 ...
Page 828: ...17 Power Down Mode Rev 1 00 Jan 10 2008 Page 798 of 1658 REJ09B0261 0100 ...
Page 846: ...18 Timer Unit TMU Rev 1 00 Jan 10 2008 Page 816 of 1658 REJ09B0261 0100 ...
Page 1292: ...24 Multimedia Card Interface MMCIF Rev 1 00 Jan 10 2008 Page 1262 of 1658 REJ09B0261 0100 ...
Page 1326: ...25 Audio Codec Interface HAC Rev 1 00 Jan 10 2008 Page 1296 of 1658 REJ09B0261 0100 ...
Page 1482: ...28 General Purpose I O Ports GPIO Rev 1 00 Jan 10 2008 Page 1452 of 1658 REJ09B0261 0100 ...
Page 1538: ...30 User Debugging Interface H UDI Rev 1 00 Jan 10 2008 Page 1508 of 1658 REJ09B0261 0100 ...
Page 1688: ...Appendix Rev 1 00 Jan 10 2008 Page 1658 of 1658 REJ09B0261 0100 ...
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