Texas Instruments TMS320DM357, User Manual

Page: 32 / 167

2.3.2.8 Source B Index (SRCBIDX)
2.3.2.9 Destination B Index (DSTBIDX)
2.3.2.10 Source C Index (SRCCIDX)
2.3.2.11 Destination C Index (DSTCIDX)
2.3.2.12 Link Address (LINK)
Parameter RAM (PaRAM)
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SRCBIDX is a 16-bit signed value (2s complement) used for source address modification between each
array in the 2nd dimension. Valid values for SRCBIDX are between –32 768 and 32 767. It provides a
byte address offset from the beginning of the source array to the beginning of the next source array. It
applies to both A-synchronized and AB-synchronized transfers. Some examples:
•
SRCBIDX = 0000h (0): no address offset from the beginning of an array to the beginning of the next
array. All arrays are fixed to the same beginning address.
•
SRCBIDX = 0003h (+3): the address offset from the beginning of an array to the beginning of the next
array in a frame is 3 bytes. For example, if the current array begins at address 1000h, the next array
begins at 1003h.
•
SRCBIDX = FFFFh (–1): the address offset from the beginning of an array to the beginning of the next
array in a frame is –1 byte. For example, if the current array begins at address 5054h, the next array
begins at 5053h.
DSTBIDX is a 16-bit signed value (2s complement) used for destination address modification between
each array in the 2nd dimension. Valid values for DSTBIDX are between –32 768 and 32 767. It provides
a byte address offset from the beginning of the destination array to the beginning of the next destination
array within the current frame. It applies to both A-synchronized and AB-synchronized transfers. See
SRCBIDX for examples.
SRCCIDX is a 16-bit signed value (2s complement) used for source address modification in the
3rd dimension. Valid values for SRCCIDX are between –32 768 and 32 767. It provides a byte address
offset from the beginning of the current array (pointed to by SRC address) to the beginning of the first
source array in the next frame. It applies to both A-synchronized and AB-synchronized transfers. Note that
when SRCCIDX is applied, the current array in an A-synchronized transfer is the last array in the frame
(
Figure 2-5 ), while the current array in an AB-synchronized transfer is the first array in the frame
( Figure 2-6 ).
DSTCIDX is a 16-bit signed value (2s complement) used for destination address modification in the
3rd dimension. Valid values are between –32 768 and 32 767. It provides a byte address offset from the
beginning of the current array (pointed to by DST address) to the beginning of the first destination array
TR in the next frame. It applies to both A-synchronized and AB-synchronized transfers. Note that when
DSTCIDX is applied, the current array in an A-synchronized transfer is the last array in the frame
(
Figure 2-5 ), while the current array in a AB-synchronized transfer is the first array in the frame
( Figure 2-6 ).
The EDMA3CC provides a mechanism, called linking, to reload the current PaRAM set upon its natural
termination (that is, after the count fields are decremented to 0) with a new PaRAM set. The 16-bit
parameter LINK specifies the byte address offset in the PaRAM from which the EDMA3CC loads/reloads
the next PaRAM set during linking.
You must program the link address to point to a valid aligned 32-byte PaRAM set. The 5 LSBs of the LINK
field should be cleared to 0.
The EDMA3CC ignores the upper 2 bits of the LINK entry, allowing the programmer the flexibility of
programming the link address as either an absolute/literal byte address or use the PaRAM-base-relative
offset address. Therefore, if you make use of the literal address with a range from 4000h to 7FFFh, it will
be treated as a PaRAM-base-relative value of 0000h to 3FFFh.
32 EDMA3 Architecture SPRUG34 – November 2008
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