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CN8474AEPF 参数 Datasheet PDF下载

CN8474AEPF图片预览
型号: CN8474AEPF
PDF下载: 下载PDF文件 查看货源
内容描述: 多通道同步通信控制器( MUSYCC ™ ) [Multichannel Synchronous Communications Controller (MUSYCC?)]
分类和应用: 通信控制器
文件页数/大小: 221 页 / 2104 K
品牌: CONEXANT [ CONEXANT SYSTEMS, INC ]
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6.0 Basic Operation  
CN8478/CN8474A/CN8472A/CN8471A  
6.3 Channel Operation  
Multichannel Synchronous Communications Controller (MUSYCC™)  
6.3.2 Group Base Pointer  
For the Group Base Pointer the host must allocate a 2 kB bound memory segment  
for Channel Group 0. The value calculated as the address for a Group Base  
Structure must be written into MUSYCCs Group 0 Base Pointer register using a  
PCI write cycle. After PCI configuration, this is a simple memory access by the  
host.  
A service request does not exist to update this pointer in MUSYCC because  
all service requests reference this pointer value to gain access to the shared  
memory resident group structure and the descriptors within it.  
The components of the Group Base Pointer are listed in Table 6-1.  
#define SIZE_OF_GROUP_STRUCTURE 1564  
#define GROUP_STR_BOUNDARY 2048  
GroupStr0.pGroupBase = malloc( SIZE_OF_GROUP_STRUCTURE + GROUP_STR_BOUNDARY );  
GroupStr0.pGroupBase = ( GroupStr0.pGroupBase + GROUP_STR_BOUNDARY ) &  
~(GROUP_STR_BOUNDARY -1);  
/* group base pointer pointers must be a 2K byte aligned address */  
/* above, there is enough space to first move forward 2K bytes, then */  
/* lop off the 2K automatically. This will bring the pointer back */  
/* to the original address or give us the next 2K byte boundary address */  
/* IMPORTANT NOTE: be sure to save away the original pointer returned by the */  
/* memory access routine as that same value will be required to free the space.  
*/  
/* must write directly into MUSYCC register */  
*(MUSYCC_FUNC_0_BAR + GROUP_BASE_OFFSET) = GroupStr0.pGroupBase;  
Table 6-1. Example—Components of Group Base Pointer  
Descriptor  
Component of Descriptor  
Value of Components  
Group  
Base  
Pointer to a shared memory segment large enough  
for all configuration descriptors for Channel Group 0.  
Return pointer from “malloc ( )” adjusted  
to a 2 kB boundary.  
Pointer  
6-10  
Conexant  
100660E  
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