thlmenezes / FPGRARS

A RISC-V simulator with built-in graphics display and keyboard input

FPGRARS

Fast Pretty Good RISC-V Assembly Rendering System

(name may change at any moment)

FPGRARS aims to provide a RISC-V assembly simulator with 8-bit color graphics display and keyboard input, similar to RARS, but faster.

Running FPGRARS

First, head over to the latest release and download the appropriate executable. Then, you can run a RISC-V assembly file either by running ./fpgrars your_riscv_file.s in a terminal or by dragging the .s onto the executable. If you're on Linux, you might need to chmod +x fpgrars-x86_64-unknown-linux-gnu for FPGRARS to work.

Supported ecalls

Description	a7	Input	Output
Print integer	1	a0 = integer to print
Print float	2	fa0 = float to print
Print string	4	a0 = address of the string
Read int	5		a0 = the read integer
Read float	6		fa0 = the read float
Sbrk	9	a0 = bytes to allocate (>= 0)	a0 = address of the allocated chunk
Exit	10
Stop execution	110
Print char	11	a0 = the char
Time	30		a0 = low bits of milliseconds since unix epoch, a1 = high bits
Midi out	31	a0 = pitch (note), a1 = duration in ms, a2 = instrument (in range 0-127), a3 = volume (also 0-127)	Async sound
Sleep ms	32	a0 = number of milliseconds to sleep
Midi out sync	33	a0 = pitch (note), a1 = duration in ms, a2 = instrument (in range 0-127), a3 = volume (also 0-127)	Synchronous sound
Print hex integer	34	a0 = integer to print
Print unsigned integer	36	a0 = unsigned integer to print
Rand seed	40	does nothing for now
Rand int	41		a0 = random integer
Rand int range	42	a0 is discarded, a1 = upper bound	a0 = random integer in [0, a1)
Rand float	43		fa0 = random float in [0, 1)
Clear screen	48 or 148	a0 = color, a1 = frame
Open file	1024	a0 = address of the null-terminated string for the path, a1 = 0 (read mode), 1 (write mode) or 9 (append mode)	a0 = the file descriptor or -1 if error
Close file	57	a0 = a file descriptor
Seek	62	a0 = a file descriptor, a1 = the offset to seek, a2 = 0 (seek from the start of the file), 1 (from the current position) or 2 (from the end)	a0 = the selected position from the start of the file
Read	63	a0 = a file descriptor, a1 = address of the buffer, a2 = maximum length to read	a0 = number of bytes read or -1 if error
Write	64	a0 = a file descriptor, a1 = address of the buffer, a2 = length to write	a0 = number of bytes written of -1 if error