4 ms·

An enum with the opcodes would have been a lot nicer. I guess theres no time to lose in a competition with the rest of the world to come up with stuff on a one

An enum with the opcodes would have been a lot nicer. I guess theres no time to lose in a competition with the rest of the world to come up with stuff on a one page of paper CPU.

a1k0n 15y ago
And I'm pretty sure the O register isn't supposed to be set in all cases. And what was lit[] supposed to be for?
- jpd 15y ago
  He needs 'lit' so dcpu_opr() can uniformly return a pointer for all results, including literal values.
- swetland 15y ago
  Yeah, think you're right. I'm out of spec there. That's what you get for trying to be cute. Fixed now.
  - a1k0n 15y ago
    I think your lit table also implies you can write to literals. So I can 'SET 2, 0x1f; SET A, 2' and now A is 0x1f.
    - swetland 15y ago
      There's a check in the writeback phase that prevents that.
      - a1k0n 15y ago
        Ah-ha, yes there is. Sorry.
cpeterso 15y ago
I'm sure pull requests would be graciously considered. :)
- revelation 15y ago
  Sorry, this came off a bit rude. I just saw the Go version having the same magic numbers all over instead of using a straightforward enum for no cost, so I felt like this was worth mentioning. On the other hand, I feel that building all kinds of stuff around notchs MMO-CPU is just an outlet for all of the excitement that has built up. I guess its upon Mojang to deliver and stop people from diverting off course.
  - eridius 15y ago
    I think you're a bit prejudiced against "magic numbers". If a number is used only once in the entire program, why bother giving it an enum? Just write a comment explaining what it is. That's what I did with the Go implementation.
    - dizidoro 15y ago
      I hate magic numbers, i believe comments should be made as last resort. The code should be self-documenting. It's about reading and understanding the code easier. One thing that i learned wit CS is that it's all about making higher abstractions, making the logic closer to the domain you are modeling. If there is a word that resumes CS, i would say abstraction. Thats why we have high level languages, OOP, Operating Sytems, folders and files and etc.
      - chj 15y ago
        Normally enum is better. Here enum is not a good idea if you have a switch case like: switch (val) { /* val is uint8_t / case OP_XXX: break; case OP_YYY: break; case OP_ZZZ: break; } Looks nice, but in debugging, you have no idea where we are going when you set a breakpoint at the switch. because the val is not an enum type, so debugger can't make the job easier for you. Now it is much better: switch (val) { / val is uint8_t / case 0: / XXX / break; case 1: / YYY / break; case 2: / ZZZ */ break; }

An enum with the opcodes would have been a lot nicer. I guess theres no time to lose in a competition with the rest of the world to come up with stuff on a one page of paper CPU.

a1k0n 15y ago

And I'm pretty sure the O register isn't supposed to be set in all cases. And what was lit[] supposed to be for?

jpd 15y ago
He needs 'lit' so dcpu_opr() can uniformly return a pointer for all results, including literal values.
swetland 15y ago
Yeah, think you're right. I'm out of spec there. That's what you get for trying to be cute. Fixed now.
- a1k0n 15y ago
  I think your lit table also implies you can write to literals. So I can 'SET 2, 0x1f; SET A, 2' and now A is 0x1f.
  - swetland 15y ago
    There's a check in the writeback phase that prevents that.
    - a1k0n 15y ago
      Ah-ha, yes there is. Sorry.

cpeterso 15y ago

I'm sure pull requests would be graciously considered. :)

revelation 15y ago
Sorry, this came off a bit rude. I just saw the Go version having the same magic numbers all over instead of using a straightforward enum for no cost, so I felt like this was worth mentioning. On the other hand, I feel that building all kinds of stuff around notchs MMO-CPU is just an outlet for all of the excitement that has built up. I guess its upon Mojang to deliver and stop people from diverting off course.
- eridius 15y ago
  I think you're a bit prejudiced against "magic numbers". If a number is used only once in the entire program, why bother giving it an enum? Just write a comment explaining what it is. That's what I did with the Go implementation.
  - dizidoro 15y ago
    I hate magic numbers, i believe comments should be made as last resort. The code should be self-documenting. It's about reading and understanding the code easier. One thing that i learned wit CS is that it's all about making higher abstractions, making the logic closer to the domain you are modeling. If there is a word that resumes CS, i would say abstraction. Thats why we have high level languages, OOP, Operating Sytems, folders and files and etc.
    - chj 15y ago
      Normally enum is better. Here enum is not a good idea if you have a switch case like: switch (val) { /* val is uint8_t / case OP_XXX: break; case OP_YYY: break; case OP_ZZZ: break; } Looks nice, but in debugging, you have no idea where we are going when you set a breakpoint at the switch. because the val is not an enum type, so debugger can't make the job easier for you. Now it is much better: switch (val) { / val is uint8_t / case 0: / XXX / break; case 1: / YYY / break; case 2: / ZZZ */ break; }