nv2a-vsh 0.1.1

Assembler/disassembler for the Xbox nv2a vertex shader

Trivial assembler for the nv2a vertex shader.

The Cg -> vp20 path performs various optimizations that sometimes make it hard to force unusual test conditions. This assembler performs no optimizations, and simply translates operands into machine code.

Instructions

• ADD
• ARL
• DP3
• DP4
• DPH
• DST
• EXPP
• LIT
• LOGP
• MAD
• MAX
• MIN
• MOV
• MUL
• RCC
• RCP
• RSQ
• SGE
• SLT

Registers

Temporary registers

• r0 - r11

Constant/uniform registers

• c0 - c191

Constant registers may also use relative addressing via bracket syntax. E.g., c[A0 + 12]

Address register

• a0

May only be set via the ARL instruction. E.g., ARL a0, v12

Inputs

• v0, iPos
• v1, iWeight
• v2, iNormal
• v3, iDiffuse
• v4, iSpecular
• v5, iFog
• v6, iPts
• v7, iBackDiffuse
• v8, iBackSpecular
• v9, iTex0
• v10, iTex1
• v11, iTex2
• v12, iTex3
• v13
• v14
• v15

Outputs

• oB0, oBackDiffuse
• oB1, oBackSpecular
• oD0, oDiffuse
• oD1, oSpecular
• oFog
• oPos
• oPts
• oTex0, oT0
• oTex1, oT1
• oTex2, oT2
• oTex3, oT3

Swizzle/destination masks

• xyzw
• rgba

Uniform macros

A simple macro syntax is supported to allow symbolic naming for c-register access. Two types are currently implemented, vector and matrix4.

A vector type aliases a single c register. E.g., to give a symbolic name to c10: #uniform_name vector 10. The macro can then be used in subsequent instructions; e.g., mov r0, #uniform_name.

A matrix4 type aliases a contiguous set of 4 c registers. E.g., to give a symbolic name to a model matrix passed at 'c96': #my_model_matrix matrix4 96. To access the second row: mul r0, v0.y, #my_model_matrix[1].