RISC-V: Difference between revisions
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x111xxxxx1111111 Reserved for ≥192-bits |
x111xxxxx1111111 Reserved for ≥192-bits |
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===Word Size=== |
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* [http://stackoverflow.com/questions/29618439/what-is-the-size-of-integer-in-8-bit-16-bit-32-bit-processors-microcontrollersOn an 8-bit Atmel AVR Arduino, sizeof(int) returns 2 (e.g. 16-bits) when compiled with GCC 4.3.2 (WinAVR 20081205)] |
* [http://stackoverflow.com/questions/29618439/what-is-the-size-of-integer-in-8-bit-16-bit-32-bit-processors-microcontrollersOn an 8-bit Atmel AVR Arduino, sizeof(int) returns 2 (e.g. 16-bits) when compiled with GCC 4.3.2 (WinAVR 20081205)] |
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* [http://electronics.stackexchange.com/questions/203252/what-determines-sizeofint int is a C type. The ATMega's have no concept of it, they work only with 8bit bytes (because they have 8bit AVR CPUs).] |
* [http://electronics.stackexchange.com/questions/203252/what-determines-sizeofint int is a C type. The ATMega's have no concept of it, they work only with 8bit bytes (because they have 8bit AVR CPUs).] |
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Revision as of 06:54, 2 November 2016
Minimum Sized ISA
Registers
- R32, 5-Bits specify register. 32 registers
- 4-bits will get you 16 (14)
- 3-Bits will get you 8 (6)
- 2 registers are fixed. R0 is always zero, XLEN-1 (last reg) is PC.
Op Codes
- All the 32-bit instructions in the base ISA have their lowest two bits set to 11
xxxxxxxxxxxxxxaa 16-bit (aa != 11) xxxxxxxxxxxbbb11 32-bit (bbb != 111) xxxxxxxxxx011111 48-bit xxxxxxxxx0111111 64-bit xnnnxxxxx1111111 (80+16*nnn)-bit, nnn != 111 x111xxxxx1111111 Reserved for ≥192-bits