callc (sm4 - asm)
Conditionally calls a subroutine marked by where the label l# appears in the program.
| callc{_z|_nz} src0.select_component, l# |
|---|
| Item | Description |
|---|---|
| src0 |
[in] The component on which to test the condition. |
| l# |
[in] The label of the subroutine. |
Remarks
When a ret is encountered, return execution to the instruction after this call.
The token format contains the offset of the corresponding label in the Shader as a convenience.
The following example shows the call instruction.
...
callc_z r1.y, l3 // if all bits in r0.x are 0, call l3
callc_nz r2.z, l3 // if any bit in r0.x is nonzero, call l3
...
ret
label l3
...
retc_nz r0.x
...
ret
Restrictions
- Subroutines can nest 32 deep.
- The return address stack is managed transparently by the implementation.
- If there are already 32 entries on the return address stack and a call is issued, the call is skipped over.
- There is no automatic parameter stack. The application can use an indexable temporary register array (x#[]) to manually implement a stack. However, the subroutine call return addresses are not visible and are orthogonal to any manual stack management done by the application.
- Indexing of the l# parameter is not permitted.
- The 32-bit register supplied by src0 is tested at a bit level. If any bit is nonzero, callc_nz will perform the call. If all bits are zero, callc_z will perform the call.
- Recursion is not permitted.
This instruction applies to the following shader stages:
| Vertex Shader | Geometry Shader | Pixel Shader |
|---|---|---|
| x | x | x |
Minimum Shader Model
This function is supported in the following shader models.
| Shader Model | Supported |
|---|---|
| Shader Model 5 | yes |
| Shader Model 4.1 | yes |
| Shader Model 4 | yes |
| Shader Model 3 (DirectX HLSL) | no |
| Shader Model 2 (DirectX HLSL) | no |
| Shader Model 1 (DirectX HLSL) | no |