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NDMA: Difference between revisions

Created page with "== Registers == There's 4 NDMA channels. Arm7/Arm9 have separate NDMA. {| class="wikitable" border="1" ! NAME ! ADDRESS ! WIDTH |- | REG_NDMA_MASTER_CNT | 0x04004100 | 4 |..."
 
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Line 7: Line 7:
!  WIDTH
!  WIDTH
|-
|-
|  REG_NDMA_MASTER_CNT
|  REG_NDMAGCNT
|  0x04004100
|  0x04004100
|  4
|  4
|-
|-
|  REG_NDMA_SRC(n)
|  REG_NDMASAD(n)
|  0x04004104 + (n*0x1c)
|  0x04004104 + (n*0x1c)
|  4
|  4
|-
|-
|  REG_NDMA_DEST(n)
|  REG_NDMADAD(n)
|  0x04004108 + (n*0x1c)
|  0x04004108 + (n*0x1c)
|  4
|  4
|-
|-
|  REG_NDMA_NUM0(n)
|  REG_NDMATCNT(n)
|  0x0400410c + (n*0x1c)
|  0x0400410c + (n*0x1c)
|  4
|  4
|-
|-
|  REG_NDMA_NUM1(n)
|  REG_NDMAWCNT(n)
|  0x04004110 + (n*0x1c)
|  0x04004110 + (n*0x1c)
|  4
|  4
|-
|-
|  REG_NDMA_14(n)
|  REG_NDMABCNT(n)
|  0x04004114 + (n*0x1c)
|  0x04004114 + (n*0x1c)
|  4
|  4
|-
|-
|  REG_NDMA_CLEAR(n)
|  REG_NDMAFDATA(n)
|  0x04004118 + (n*0x1c)
|  0x04004118 + (n*0x1c)
|  4
|  4
|-
|-
|  REG_NDMA_CNT(n)
|  REG_NDMACNT(n)
|  0x0400411c + (n*0x1c)
|  0x0400411c + (n*0x1c)
|  4
|  4
|}
|}


== REG_NDMA_MASTER_CNT ==
== REG_NDMAGCNT ==
{| class="wikitable" border="1"
{| class="wikitable" border="1"
!  BIT
!  BIT
!  DESCRIPTION
!  DESCRIPTION
|-
|-
|  15-0
|  19-16
|  ?
|  Cycle selection.
|-
|  16
|  Unknown, set when initialized by Arm7?
|-
|  17
|  Unknown, set when initialized by Arm9?
|-
|  18
|  Unknown, set when initialized by Arm7/Arm9?
|-
|  30-19
|  ?
|-
|-
|  31
|  31
|  Might be master NDMA enable, when initialized this is set?
|  DMA arbitration method. 0=Fixed method, 1=Round robin
|}
|}


== REG_NDMA_SRC ==
== REG_NDMASAD ==
{| class="wikitable" border="1"
{| class="wikitable" border="1"
!  BIT
!  BIT
Line 70: Line 58:
|-
|-
|  31-0
|  31-0
|  Source data address.
|  Source data address. Must be multiple of 4.
|}
|}
Like old DMA, REG_NDMA_SRC is copied to internal registers when written to.
Like old DMA, REG_NDMASAD is copied to internal registers when written to.


== REG_NDMA_DEST ==
== REG_NDMADAD ==
{| class="wikitable" border="1"
{| class="wikitable" border="1"
!  BIT
!  BIT
Line 80: Line 68:
|-
|-
|  31-0
|  31-0
|  Destination data address.
|  Destination data address. Must be multiple of 4.
|}
|}
Like old DMA, REG_NDMA_DEST is copied to internal registers when written to.
Like old DMA, REG_NDMADAD is copied to internal registers when written to.


== REG_NDMA_NUM0 ==
== REG_NDMATCNT ==
{| class="wikitable" border="1"
{| class="wikitable" border="1"
!  BIT
!  BIT
!  DESCRIPTION
!  DESCRIPTION
|-
|-
|  31-0
|  27-0
|  Number of bytes to copy/write, see REG_NDMA_CNT bit28.
|  Total number of words transferred.
|}
|}


== REG_NDMA_NUM1 ==
== REG_NDMAWCNT ==
{| class="wikitable" border="1"
{| class="wikitable" border="1"
!  BIT
!  BIT
!  DESCRIPTION
!  DESCRIPTION
|-
|-
|  31-0
|  23-0
|  Number of bytes to copy/write, see REG_NDMA_CNT bit28.
|  Number of words to transfer.
|}
|}


== REG_NDMA_14 ==
== REG_NDMABCNT ==
{| class="wikitable" border="1"
{| class="wikitable" border="1"
!  BIT
!  BIT
!  DESCRIPTION
!  DESCRIPTION
|-
|-
|  31-0
|  15-0
|  Time related?
|  Interval timer.
|-
|  17-16
|  Prescaler. 0=System freq, 1=1/4th freq, 2=1/16th freq, 3=1/64th freq.
|}
|}


== REG_NDMA_CLEAR ==
== REG_NDMAFDATA ==
{| class="wikitable" border="1"
{| class="wikitable" border="1"
!  BIT
!  BIT
Line 117: Line 108:
|-
|-
|  31-0
|  31-0
|  Value to write to destination instead of copying when REG_NDMA_CNT bit13 and bit14 are set.
|  Fill data.
|}
|}


== REG_NDMA_CNT ==
== REG_NDMACNT ==
{| class="wikitable" border="1"
{| class="wikitable" border="1"
!  BIT
!  BIT
!  DESCRIPTION
!  DESCRIPTION
|-
|-
|  10-0
|  11-10
|  ?
|  Destination address update method. 0=Increment, 1=Decrement, 2=Fixed.
|-
|-
|  11
|  12
|  Fixed destination address when set.
|  Destination address reload flag.
|-
|-
|  12
|  14-13
|  ?
|  Source address update method. 0=Increment, 1=Decrement, 2=Fixed, 3=No address (for filling)
|-
|-
|  13
|  15
|  When set clear data with the value REG_NDMA_CLEAR instead of copying.
|  Source address reload flag.
|-
|-
|  14
|  19-16
|  Fixed source address when set.
|  Block transfer word count = (1<<x) words.
|-
|-
|  27-15
|  27-24
|  ?
|  Startup mode.
|-
|-
|  28
|  28
|  Set when REG_NDMA_NUM0 was set, clear when REG_NDMA_NUM1 was set.
|  Immediate mode.
|-
|  29
|  Repeating mode.
|-
|-
|  30
|  30
Line 150: Line 144:
|-
|-
|  31
|  31
|  Enable/busy
|  Enable/busy flag.
|}
|}
== Startup modes (27-24) for ARM9 ==
{| class="wikitable" border="1"
!  VALUE
!  DESCRIPTION
|-
|  0
|  Timer 0
|-
|  1
|  Timer 1
|-
|  2
|  Timer 2
|-
|  3
|  Timer 3
|-
|  4
|  Game Card
|-
|  6
|  V-Blank
|-
|  7
|  H-Blank
|-
|  8
|  Display
|-
|  9
|  Work RAM
|-
|  10
|  Geometry FIFO
|-
|  11
|  Camera
|}
== Startup modes (27-24) for ARM7 ==
{| class="wikitable" border="1"
!  VALUE
!  DESCRIPTION
|-
|  0
|  Timer 0
|-
|  1
|  Timer 1
|-
|  2
|  Timer 2
|-
|  3
|  Timer 3
|-
|  4
|  Game Card
|-
|  6
|  V-Blank
|-
|  7
|  Wireless
|-
|  8
|  SD I/F 1
|-
|  9
|  SD I/F 2
|-
|  10
|  AES in
|-
|  11
|  AES out / MIC(?)
|-
|  12
|  MIC(?)
|}
== Block transfers ==
First, a word is always 32 bits. Second, the block transfer specified in REG_NDMACNT is the smallest atom of data that will be transferred in a burst. The bus is monopolized until this block is transferred, without splitting up.
The next block transfer will happen after the specified time in the REG_NDMABCNT interval timer, until done.
== Immediate mode ==
Transfers the words specified in REG_NDMAWCNT immediately following block transfer rules. REG_NDMATCNT and repeating mode are ignored.
== Repeating mode ==
Transfers the words specified in REG_NDMAWCNT following the startup mode event. REG_DMATCNT is ignored.
== No immediate and no repeating mode ==
Transfers the words specified in REG_NDMAWCNT for each startup event, and gets disabled when the total number of words in REG_NDMATCNT are transferred.
Retrieved from "https://dsibrew.org/wiki/NDMA"