# Ztrans - transcendental operations

See:

* <http://bugs.libre-riscv.org/show_bug.cgi?id=127>
* <https://www.khronos.org/registry/spir-v/specs/unified1/OpenCL.ExtendedInstructionSet.100.html>

Extension subsets:

* **Ztrans**: standard transcendentals (best suited to 3D)
* **ZtransExt**: extra functions (useful, not generally needed for 3D)
* **ZtransAdv**: much more complex to implement in hardware

[[!toc levels=2]]

# List of 2-arg opcodes

[[!table  data="""
opcode    | Description           | pseudo-code                | Extension |
FATAN2    | atan2 arc tangent     | rd = atan2(rs2, rs1)       | Ztrans    |
FATAN2PI  | atan arc tangent / pi | rd = atan2(rs2, rs1) / pi  | ZtransExt |
FPOW      | x power of y          | rd = pow(rs1, rs2)         | ZtransAdv |
FROOT     | x power 1/y           | rd = pow(rs1, 1/rs2)       | ZtransAdv |
"""]]

# List of 1-arg opcodes

[[!table  data="""
opcode   | Description              | pseudo-code             | Extension |
FCBRT    | Cube Root                | rd = pow(rs1, 3)        | Ztrans    |
FEXP2    | power-of-2               | rd = pow(2, rs1)        | Ztrans    |
FLOG2    | log2                     | rd = log2(rs1)          | Ztrans    |
FEXPM1   | exponent minus 1         | rd = pow(e, rs1) - 1.0  | Ztrans    |
FLOG1P   | log plus 1               | rd = log(e, 1 + rs1)    | Ztrans    |
FEXP     | exponent                 | rd = pow(e, rs1)        | ZtransExt |
FLOG     | natural log (base e)     | rd = log(e, rs1)        | ZtransExt |
FEXP10   | power-of-10              | rd = pow(10, rs1)       | ZtransExt |
FLOG10   | log base 10              | rd = log10(rs1)         | ZtransExt |
FSIN     | sin (radians)            |                         | Ztrans    |
FCOS     | cos (radians)            |                         | Ztrans    |
FTAN     | tan (radians)            |                         | Ztrans    |
FASIN    | arcsin (radians)         | rd = asin(rs1)          | Ztrans    |
FACOS    | arccos (radians)         | rd = acos(rs1)          | Ztrans    |
FSINPI   | sin times pi             | rd = sin(pi * rs1)      | ZtransExt |
FCOSPI   | cos times pi             | rd = cos(pi * rs1)      | ZtransExt |
FSINH    | hyperbolic sin (radians) |                         | ZtransExt |
FCOSH    | hyperbolic cos (radians) |                         | ZtransExt |
FTANH    | hyperbolic tan (radians) |                         | ZtransExt |
FASINH   | inverse hyperbolic sin   |                         | ZtransExt |
FACOSH   | inverse hyperbolic cos   |                         | ZtransExt |
FATANH   | inverse hyperbolic tan   |                         | ZtransExt |
"""]]

# Pseudo-code ops

* FRCP rd, rs1 - pseudo-code alias for rd = 1.0 / rs1
* FATAN - pseudo-code alias for rd = atan2(rs1, 1.0) - FATAN2
* FATANPI - pseudo alias for rd = atan2pi(rs1, 1.0) - FATAN2PI
* FSINCOS - fused macro-op between FSIN and FCOS (issued in that order).
* FSINCOSPI - fused macro-op between FSINPI and FCOSPI (issued in that order).