loop - vs
Start a loop...endloop block.
Syntax
| loop aL, i# |
|---|
Where:
- aL is the Loop Counter Register holding the current loop count.
- i# is a Constant Integer Register. See remarks.
Remarks
| Vertex shader versions | 1_1 | 2_0 | 2_x | 2_sw | 3_0 | 3_sw |
|---|---|---|---|---|---|---|
| loop | x | x | x | x | x |
- The Loop Counter Register (aL) holds the current loop count, and can be used for relative addressing into Constant Integer Register (c#) or Output Registers (o#) inside the loop block.
- i#.x specifies the iteration count. The legal range is [0, 255]. Note that this instruction does not increment or decrement the value of i#.x.
- i#.y specifies the initial value of the Loop Counter Register (aL) register. The legal range is [0, 255]. Note that this instruction does not increment or decrement the value of i#.y.
- i#.z specifies the step/stride size. The legal range is [-128, 127].
- i#.w is not used and must be set to 0.
- Loop blocks may be nested. See Flow Control Nesting Limits.
- When nested, the value of the Loop Counter Register (aL) refers to the immediate enclosing loop block.
- Loop blocks are allowed to be either completely inside an if* block or completely surrounding it. No straddling is allowed.
Example
loop aL, i3
add r1, r0, c2[aL]
endloop
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