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37 lines
1.3 KiB
Markdown
37 lines
1.3 KiB
Markdown
# Section 2 / Registers (Simplified)
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## Overview
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There are four highest level ideas relating to floating point operations
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on AARCH64.
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* There is another complete register set for floating point values.
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* There are alternative instructions just for floating point values.
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* There are exotic instructions that operate on sets of floating point
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values (SIMD).
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* There are instructions to go back and forth to and from the integer
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registers.
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## Floating Point Registers
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There will be a more detailed discussion of the floating point registers
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when exotic instructions such as SIMD are discussed. For now, it is
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sufficient to discuss the less exotic aliases of the floating point
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registers.
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We say aliases because, like the integer registers, how you reference a
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floating point register determines how it is interpreted.
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*NOTE NOTE NOTE* To keep to our promise of simplicity for now, consider only
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`B0`, `H0`, `S0` and `D0`. The remainder of the image ([from The Eclectic Light
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Company](https://eclecticlight.co/2021/08/23/code-in-arm-assembly-lanes-and-loads-in-neon/))
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deals with SIMD, covered later.
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It is worth noting early and often that you should not mix dealing
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with different precisions assuming that because of the overlaps in
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space, you'll get a meaningful result.
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