openfirmware

ware/tree/master/cpu/x86 purpose: From Forth, call the C subroutine whose address is on the stack https://github.com/openbios/openfirmware/blob/master/cpu/x86... purpose: Tools for creating disembodied assembly code sequences https://github.com/openbios/openfirmware/blob/master/cpu/x86... purpose: Forth access words for special 386 registers https://github.com/openbios/openfirmware/blob/master/cpu/x86... purpose: After a breakpoint, displays a backtrace of C stack frames. https://github.com/openbios/openfirmware/blob/master/cpu/x86... purpose: 386 disassembler. https://github.com/openbios/openfirmware/blob/master/cpu/x86... purpose: Access to I/O ports and physical addresses under Linux https://github.com/openbios/openfirmware/blob/master/cpu/x86... https://github.com/openbios/openfirmware/blob/master/cpu/x86... \ One of the very best features of FORTH assemblers is the ability \ to use structured conditionals instead of branching to nonsense \ labels. : IF >MARK swap long-offsets @ if dup h# eb = if drop h# e9 asm8, else prefix-0f h# 10 + asm8, then real? if 0 asm16, else 0 asm32, then else ASM8, 0 asm8, then ; : THEN >RESOLVE ; : BEGIN <MARK ; : UNTIL <RESOLVE ; : AHEAD 0EB IF ; : ELSE AHEAD BUT THEN ; : AGAIN 0EB UNTIL ; : WHILE IF BUT ; : REPEAT AGAIN THEN ; \ These conditional test words leave the opcodes of conditional \ branches to be used by the structured conditional words. \ For example, \ 5 # ECX CMP 0< IF EAX EBX ADD ELSE EAX EBX SUB THEN \ begin dx al in tbe # al and 0<> until https://github.com/openbios/openfirmware/blob/master/cpu/x86... \ Some x86 assembler macros to make it easier to write x86 early \ startup code. There are macros to set MSRs to specific values, \ to set and clear individual MSR bits, to read and write PCI \ configuration registers with the common CF8/CFC mechanism, \ and to read and write I/O ports. \ The code keeps the MSR register number in %ecx, the low 32 bits \ of the value in %eax, and the high 32 bits in %edx, consistent \ with the way the rdmsr and wrmsr machine instructions work. \ The bitset and bitclr operations work on %eax, and the -hi versions \ work on %edx. \ The I/O port operations also leave the data in %eax, so you can \ use bitset and bitclr with them too.

ers like 0, 1, -1 and others are hard coded, not just for speed but also for space: a call to a code word only takes one cell, instead of using two cells with a LIT [value]. Here's some Breshenham line code I first wrote in FORTH (Mitch Bradley's SunForth on a 68k Sun-2 with cg2 graphics board), then translated to 68k code (using the rpn FORTH assembler) -- the FORTH code is commented out before the corresponding assembly code: https://donhopkins.com/home/archive/forth/cg/line.f [...] https://news.ycombinator.com/item?id=17480298 Cool! Does it include a FORTH 6502 assembler written in FORTH? I love writing assembly code in RPN with Forth macros! You can write FORTH code with loops and conditionals and any kind of logic and parameters, that dynamically assembles machine code! Much better than your typical macro assembler. Here's some 6502 assembler for an Apple ][ SUPDUP terminal emulator that does ram card bank switching: http://www.donhopkins.com/home/archive/forth/supdup.f [...] https://news.ycombinator.com/item?id=22456471 In what way is PostScript worse than Forth? Please answer with specific details, and provide links to code if you can. I programmed a lot of Forth code before learning and moving on to programming a lot of PostScript code, so I've used each of them extensively, and much prefer PostScript, and I'm happy to show you why and explain by showing you code. [...] https://news.ycombinator.com/item?id=21968175 Kragen is right that PostScript is a lot more like Lisp or Smalltalk than Forth, especially when you use Owen Densmore's object oriented PostScript programming system (which NeWS was based on). PostScript is semantically very different and much higher level that Forth, and syntactically similar to Forth but uses totally different names (exch instead of swap, pop instead of drop, etc). [...]