Instructions - ps_2_x

This section contains reference information for the pixel shader version 2_x instructions.

There are several types of pixel shader instructions, as shown in the table. Columns to the right mean the following:

Instruction slots - Number of instruction slots used by each instruction.
Setup - A pixel shader must have a version instruction and it must be the first instruction.
Arithmetic - These instructions provide the mathematical operations in a shader.
Macro-ops - These instructions combine arithmetic instructions to provide higher level functionality. The use of macro-ops is optional. It is preferable to use macro-ops, especially the matrix multiply instructions (m3x2, m3x3, m3x4, m4x3, m4x4), because they provide optimization opportunities to the underlying implementation.
Texture - These instructions are used to load and sample texture data, and to modify texture coordinates.
Flow control - These instructions provide static and dynamic flow control to the execution of instructions.
New - These instructions are new to this version.

Instruction Set

Name	Description	Instruction slots	Setup	Arithmetic	Macro-ops	Texture	Flow Control	New
abs	Absolute value	1			x
add	Add two vectors	1		x
break	Break out of a loop...endloop or rep...endrep block	1					x	x
break_comp	Conditionally break out of a loop...endloop or rep...endrep block, with a comparison	3					x	x
break pred	Break out of a loop...endloop or rep...endrep block, based on a predicate	3					x	x
call	Call a subroutine	2					x	x
callnz	Call a subroutine if a boolean register is not zero	3					x	x
callnz pred	Call a subroutine if a predicate register is not zero	3					x	x
cmp	Compare source to 0	1		x
crs	Cross product	2			x
dcl	Map a vertex element type to an input vertex register	0	x
dcl_textureType	Declare the texture dimension for a sampler	0	x
def	Define constants	0	x
dp2add	2-D dot product and add	1		x
dp3	3-D dot product	1		x
dp4	4-D dot product	1		x
dsx	Rate of change in the x-direction	2		x				x
dsy	Rate of change in the y direction	2		x				x
else	Begin an else block	1					x	x
endif	End an if...else block	1					x	x
endrep	End of a repeat block	2					x	x
exp	Full precision 2^x	1			x			x
frc	Fractional component	1			x
if	Begin an if block	3					x	x
if comp	Begin an if block with a comparison	3					x	x
if pred	Begin an if block with predication	3					x	x
label	Label	0					x	x
log	Full precision log₂(x)	1			x
lrp	Linear interpolate	2			x
m3x2	3x2 multiply	2			x
m3x3	3x3 multiply	3			x
m3x4	3x4 multiply	4			x
m4x3	4x3 multiply	3			x
m4x4	4x4 multiply	4			x
mad	Multiply and add	1		x
max	Maximum	1			x
min	Minimum	1			x
mov	Move	1		x
mul	Multiply	1		x
nop	No operation	1		x
nrm	Normalize	3			x
pow	2^x	3			x
ps	Version	0	x
rcp	Reciprocal	1		x
rep	Repeat	3					x	x
ret	End of a subroutine	1					x	x
rsq	Reciprocal square root	1		x
setp	Set the predicate register	1				x		x
sincos	Sine and cosine	8			x
sub	Subtract	1		x
texkill	Kill pixel render	2(tex)				x
texld	Sample a texture	1 + 3CUBE				x
texldb	Texture sampling with level of detail (LOD) bias from w-component	6(tex)				x
texldd	Texture sampling with user-provided gradients	3				x		x
texldp	Texture sampling with projective divide by w-component	3 + 1CUBE				x

Where:

tex - 1 texture instruction slot. However, if D3DPS20CAPS_NOTEXINSTRUCTIONLIMIT is set, this instruction is counted against the instruction ( non texture) count.
1 + 3CUBE means 1 + 3 if the texture is a cube map.
3 + 1CUBE means 3 + 1 if the texture is a cube map.

Instruction Count and Nesting Depth

Shaders have restrictions for maximum instuction counts, as well as nesting depths for static and dynamic flow control instructions.

Overall Instruction Count

Total Instruction slots: 512 maximum

The maximum number of instructions run is indicated by the MaxPShaderInstructionsExecuted cap in D3DCAPS9.

On hardware that supports ps_2_0, it should be at least 96 (more if they support the flow control caps).

This can be set to the #define D3DINFINITEINSTRUCTIONS, indicating that the actual number of instructions run is unlimited.

The total number of instructions run should be clamped to the device driver D3DRS_MAXPIXELSHADERINST. The legal values for this renderstate are numbers that are powers of 2; if any other integer is set, the next nearest pow2 number is assumed. This renderstate defaults to D3DINFINITEINSTRUCTIONS.

Dynamic Flow Control Nesting Depth

D3DCAPS9.D3DPSHADERCAPS2_0.DynamicFlowControlDepth represents the nesting depth of static flow control instructions: if, break, and break_comp. The value is equal to the nesting depth of the if_comp block. The range of values for this cap is 0 to 24. If this cap is zero, the device does not support dynamic flow control instructions.

Static Flow Control Nesting Depth

D3DCAPS9.D3DPSHADERCAPS2_0.StaticFlowControlDepth represents the nesting depth of static flow control instructions: loop/rep and call/callnz. The range of values for this cap is 1 to 4. Note that loop/rep count toward the same nesting depth, and call/callnz count toward the same nesting depth. If this cap is zero, the device does not support static flow control instructions.