ESi-RISC
Introduction '''eSi-RISC''' is a configurable CPU architecture. It is available in five implementations: the eSi-1600, eSi-1650, eSi-3200, eSi-3250 and eSi-3264.The eSi-1600 and eSi-1650 feature a 16-bit data-path, while the eSi-32x0s feature 32-bit data-paths, and the eSi-3264 features a mixed 32/64-bit datapath. Each of these processors is licensed as soft IP cores, suitable for integrating into both ASICs and FPGAs.
Architecture The main features of the eSi-RISC architecture are:eSi-3250 SoC architecture* RISC-like load/store architecture. * Configurable 16-bit, 32-bit or 32/64-bit data-path. * Instructions are encoded in either 16 or 32-bits. * 8, 16 or 32 general purpose registers, that are either 16 or 32-bits wide. * 0, 8, 16 or 32 vector registers, that are either 32 or 64-bits wide. * Up to 32 external, vectored, nested and prioritizable interrupts. * Configurable instruction set including support for integer, floating-point and fixed-point arithmetic. * SIMD operations. * Optional support for user-defined instructions, such as cryptographic acceleration . * Optional caches (Configurable size and associativity). * Optional MMU supporting both memory protection and dynamic address translation. * AMBA AXI, AHB and APB bus interfaces. * Memory mapped I/O. * 5-stage pipeline. * Hardware JTAG debug.While there are many different 16 or 32-bit Soft microprocessor IP cores available, eSi-RISC is the only architecture licensed as an IP core that has both 16 and 32-bit implementations.Unlike in other RISC architectures supporting both 16 and 32-bit instructions, such as ARM/Thumb or MIPS/MIPS-16, 16 and 32-bit instructions in the eSi-RISC architecture can be freely intermixed, rather than having different modes where either all 16-bit instructions or all 32-bit instructions are executed. This improves code density without compromising performance. The 16-bit instructions support two register operands in the lower 16 registers, whereas the 32-bit instructions support three register operands and access to all 32 registers.eSi-RISC includes support for Multiprocessing. Implementations have included up to seven eSi-3250's on a single chip.
Toolchain The eSi-RISC toolchain is based on combination of a port of the GNU toolchain and the Eclipse IDE. This includes:* GCC – C/C++ compiler. * Binutils – Assembler, linker and binary utilities. * GDB – Debugger. * Eclipse – Integrated Development Environment.The C library is Newlib and the C++ library is Libstdc++. Ported RTOSes include MicroC/OS-II, FreeRTOS, ERIKA Enterprise and Phoenix-RTOS
References
External links *  eSi-RISC homepage