8-14
MPC8240 Integrated Processor User’s Manual
DMA Descriptors for Chaining Mode
8.6.1 Descriptors in Big-Endian Mode
In big-endian byte ordering mode(MSR[LE] = 0), the descriptors in local memory should
be programmed with data appearing in ascending significant byte order.
For example, a big-endian mode descriptor’s data structure is as follows:
struct {
double a;
/* 0x1122334455667788 double word */
double b;
/* 0x55667788aabbccdd double word */
double c;
/* 0x8765432101234567 double word */
double d;
/* 0x0123456789abcdef double word */
} Descriptor;
Results: Source Address = 0x44332211 <MSB..LSB>
Destination Address = 0x88776655 <MSB..LSB>
Next Descriptor Address = 0x21436587 <MSB..LSB>
Byte Count = 0x67452301 <MSB..LSB>
Note that the descriptor
struct
must be aligned on an 8-word (32-byte) boundary.
8.6.2 Descriptors in Little-Endian Mode
In little-endian byte ordering mode(MSR[LE] = 1), the descriptor in local memory should
be programmed with data appearing in descending significant byte order.
For example, a little-endian mode descriptor’s data structure is as follows:
struct {
double a;
/* 0x8877665544332211 double word */
double b;
/* 0x1122334488776655 double word */
double c;
/* 0x7654321012345678 double word */
double d;
/* 0x0123456776543210 double word */
} Descriptor;
Results: Source Address = 0x44332211 <MSB..LSB>
Destination Address = 0x88776655 <MSB..LSB>
Next Descriptor Address = 0x12345678 <MSB..LSB>
Byte Count = 0x76543210 <MSB..LSB>
Note that the descriptor struct must be aligned on an 8-word (32-byte) boundary.
Summary of Contents for MPC8240
Page 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Page 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Page 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Page 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Page 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Page 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Page 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Page 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Page 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Page 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Page 516: ...16 14 Watchpoint Trigger Applications ...
Page 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Page 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Page 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...