On Tue, Jan 12, 2021 at 11:15:38PM +0100, Philippe Mathieu-Daudé wrote: > On 1/12/21 9:44 PM, Richard Henderson wrote: > > On 1/12/21 8:41 AM, Philippe Mathieu-Daudé wrote: > >> Some ISA use a dot in their opcodes. Allow the decodetree > >> script to process them. The dot is replaced by an underscore > >> in the generated code. > > > > Given that you then have to remember to use '_' on the C side, what > > advantage > > does this give? > > The direct advantage is you can copy/paste the opcode in a PDF viewer > without having to edit it :) > > See i.e. some Loongson opcodes [*]: > > MULT.G 011100 ..... ..... ..... 00000 010000 @rs_rt_rd > DMULT.G 011100 ..... ..... ..... 00000 010001 @rs_rt_rd > MULTU.G 011100 ..... ..... ..... 00000 010010 @rs_rt_rd > DMULTU.G 011100 ..... ..... ..... 00000 010011 @rs_rt_rd > > DIV.G 011100 ..... ..... ..... 00000 010100 @rs_rt_rd > DDIV.G 011100 ..... ..... ..... 00000 010101 @rs_rt_rd > DIVU.G 011100 ..... ..... ..... 00000 010110 @rs_rt_rd > DDIVU.G 011100 ..... ..... ..... 00000 010111 @rs_rt_rd > > MOD.G 011100 ..... ..... ..... 00000 011100 @rs_rt_rd > DMOD.G 011100 ..... ..... ..... 00000 011101 @rs_rt_rd > MODU.G 011100 ..... ..... ..... 00000 011110 @rs_rt_rd > DMODU.G 011100 ..... ..... ..... 00000 011111 @rs_rt_rd > > The other - remote - advantage I see is when using a disassembler > based on decodetree (as AVR does), the opcode displayed also matches > the specs. We are not yet there with MIPS, but I have something in > progress...
Interesting. So, the decodetree format is not used exclusively inside the QEMU source tree, but also by other projects? Is there a specification somewhere else? > > [*] https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg02509.html > -- Eduardo