Nintendo Switch Brew

GPU: Difference between revisions

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== Command Structure ==
== Command Structure ==
{| class="wikitable"
{| class="wikitable" border="1"
|-
|-
! scope="col"| Bits
! Bits || Description
! scope="col"| Description
|-
|-
|12-0
| 2-12 || Method address
|Method
|-
|-
|15-13
| 13-15 || Method subchannel
|Subchannel
|-
|-
|27-16
| 16-28 || Method count, immediate-data or [[#Tertiary opcode|tertiary opcode]]
|Argument count (in 32-bits Words) or inline data (see below)
|-
|-
|28?
| 29-31 || [[#Secondary opcode|Secondary opcode]]
|Hmm?
|-
|31-29
|[[#Submission_mode|Submission mode]]
|}
|}


Note: Methods are treated as 4-byte addressable locations, and hence their numbers are written down multiplied by 4.
Methods are treated as 4-byte addressable locations, and hence their numbers are written down multiplied by 4. The command's arguments, when present, follow the command word immediately.


Note: The command's arguments, when present, follow the command word immediately.
=== Secondary opcode ===
 
{| class="wikitable" border="1"
=== Submission mode ===
|-
{| class="wikitable"
! Mode || Description
|-
| 0 || [[#GRP0_USE_TERT|GRP0_USE_TERT]]
|-
| 1 || [[#INC_METHOD|INC_METHOD]]
|-
| 2 || Reserved
|-
| 3 || [[#NON_INC_METHOD|NON_INC_METHOD]]
|-
| 4 || [[#IMMD_DATA_METHOD|IMMD_DATA_METHOD]]
|-
|-
! scope="col"| Mode
| 5 || [[#ONE_INC|ONE_INC]]
! scope="col"| Description
! scope="col"| Offical name
|-
|-
|0
| 6 || Reserved
|Increasing mode (old)
|
|-
|-
|1
| 7 || [[#END_PB_SEGMENT|END_PB_SEGMENT]]
|Increasing mode - Tells PFIFO to read as much arguments as specified by '''argument count''', while automatically incrementing the '''method''' value. This means that each argument will be written to a different method location.
|}
|INCR
 
==== GRP0_USE_TERT ====
Tells PFIFO to read [[#Tertiary opcode|tertiary opcode]] from bits 16-17 of the command word.
 
==== INC_METHOD ====
Tells PFIFO to read as much arguments as specified by '''method count''', while automatically incrementing the '''method address''' value. This means that each argument will be written to a different method location.
 
==== NON_INC_METHOD ====
Tells PFIFO to read as much arguments as specified by '''method count'''. However, all arguments will be written to the same method location.
 
==== IMMD_DATA_METHOD ====
Tells PFIFO to read '''immediate-data''' from bits 16-28 of the command word, thus eliminating the need to pass additional words for the arguments.
 
==== ONE_INC ====
Tells PFIFO to read as much arguments as specified by '''method count''' and automatically increments the '''method address''' value once only.
 
==== END_PB_SEGMENT ====
Tells PFIFO to stop processing any further methods.
 
=== Tertiary opcode ===
{| class="wikitable" border="1"
|-
|-
|2
! Mode || Description
|Non-increasing mode (old)
|
|-
|-
|3
| 1 || GRP0_SET_SUB_DEV_MASK
|Non-increasing mode - Tells PFIFO to read as much arguments as specified by '''argument count'''. However, all arguments will be written to the same method location.
|NONINCR
|-
|-
|4
| 2 || GRP0_STORE_SUB_DEV_MASK
|Inline mode - Tells PFIFO to read '''inline data''' from bits 28-16 of the command word, thus eliminating the need to pass additional words for the arguments.
|IMM
|-
|-
|5
| 3 || GRP0_USE_SUB_DEV_MASK
|Increase-once mode - Tells PFIFO to read as much arguments as specified by '''argument count''' and automatically increments the '''method''' value once only.
|
|}
|}


== SetObject ==
== SetObject ==
In order to bind an engine object to a specific subchannel, method 0 (SetObject) must be used first. The target subchannel is specified in bits 15-13 of the command word.
In order to bind an engine object to a specific subchannel, method 0 (SetObject) must be used first. The target subchannel is specified in bits 13-15 of the command word.


After the engine object is bound to the desired subchannel, setting it's value in bits 15-13 of any subsequent command word will make PFIFO forward the command to the target engine.
After the engine object is bound to the desired subchannel, setting it's value in bits 13-15 of any subsequent command word will make PFIFO forward the command to the target engine.


This method only takes one argument, a [[#GPU_Classes|GPU Class ID]].
This method only takes one argument, a [[#GPU_Classes|GPU Class ID]].
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The above commands are added using the [[#Submission_mode|increasing mode]], since all those 4 registers are sequential.
The above commands are added using the [[#Submission_mode|increasing mode]], since all those 4 registers are sequential.


Official games sets Operation to 0 (Release), bit 4 to 1, bits 15-12 (Unit) to 0xF, and bit 28 to 1 (OneWord). The ReportSemaphorePayload value is then written by the GPU to the address pointed to by ReportSemaphoreOffset.
Official games sets Operation to 0 (Release), bit 4 to 1, bits 12-15 (Unit) to 0xF, and bit 28 to 1 (OneWord). The ReportSemaphorePayload value is then written by the GPU to the address pointed to by ReportSemaphoreOffset.
On the CPU side, the game code should wait until the value at the address pointed to by ReportSemaphoreOffset is >= to the last written value. Official code waits for this condition to be true on a loop, and won't send any further commands before that.
On the CPU side, the game code should wait until the value at the address pointed to by ReportSemaphoreOffset is >= to the last written value. Official code waits for this condition to be true on a loop, and won't send any further commands before that.


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! Word || Bits || Description
! Word || Bits || Description
|-
|-
| 0 || 6-0 || [[GPU_Texture_Formats#Texture_Formats|Texture Format]]
| 0 || 0-6 || [[GPU_Texture_Formats#Texture_Formats|Texture Format]]
|-
|-
| 0 || 9-7 || [[#Channel_Data_Type|R Channel Data Type]]
| 0 || 7-9 || [[#Channel_Data_Type|R Channel Data Type]]
|-
|-
| 0 || 12-10 || [[#Channel_Data_Type|G Channel Data Type]]
| 0 || 10-12 || [[#Channel_Data_Type|G Channel Data Type]]
|-
|-
| 0 || 15-13 || [[#Channel_Data_Type|B Channel Data Type]]
| 0 || 13-15 || [[#Channel_Data_Type|B Channel Data Type]]
|-
|-
| 0 || 18-16 || [[#Channel_Data_Type|A Channel Data Type]]
| 0 || 16-18 || [[#Channel_Data_Type|A Channel Data Type]]
|-
|-
| 1 || 31-0 || Lower 32-bits of the Texture GPU Virtual Address
| 1 || 0-31 || Lower 32-bits of the Texture GPU Virtual Address
|-
|-
| 2 || 15-0 || Higher 16-bits of the Texture GPU Virtual Address
| 2 || 0-15 || Higher 16-bits of the Texture GPU Virtual Address
|-
|-
| 4 || 15-0 || Texture Width minus 1
| 4 || 0-15 || Texture Width minus 1
|-
|-
| 5 || 15-0 || Texture Height minus 1
| 5 || 0-15 || Texture Height minus 1
|}
|}


Retrieved from "https://switchbrew.org/wiki/GPU"