cinera_handmade.network/pervognsen/bitwise/bitwise/bitwise025.hmml

[video member=pervognsen stream_platform=twitch project=bitwise title="RISC-V Dynamic Assembler, Part 2" vod_platform=youtube id=ISNB7ARzUiE annotator=Miblo]
[0:07][Recap and set the stage for the day][:speech]
[1:03][Review the current functionality of our dynamic assembler][:asm :research]
[8:05][Explain symbol allocation and back-patching][:asm :memory :research]
[18:39][Review bug fix in S-immediate encoding, and the introduction of asm_la() asm_branch() and asm_j()[ref
    author="Andrew Waterman and Krste Asanović"
    title="The RISC-V Instruction Set Manual - Volume 1: User-Level ISA"
    url=https://github.com/riscv/riscv-isa-manual/blob/master/release/riscv-spec-v2.2.pdf]][:asm :research]
[22:38][Q&A][:speech]
[22:49][@xanatos387][Hum is coming and going, when you move your head around, I think]
[23:43][Determine to implement basic memory-mapped I/O][:emulation :peripheral :speech]
[24:54][Memory-mapped I/O in emulators][:emulation :peripheral :speech]
[28:19][Abstract out the RAM handling from Hart into a new Bus struct, and propagate this change][:asm :memory]
[36:08][:Run it to see that it still works][:asm :memory]
[36:27][Implement memory-mapped I/O, hard-coded for now, enabling bus_load_word() and bus_store_word() to call getchar() and putchar() respectively][:asm :peripheral]
[40:36][Try to perform a asm_lw_imm(asm, X5, GETCHAR_ADDR)][:asm :peripheral]
[41:11][:Run it to see what it does][:asm :peripheral]
[41:46][Remove the get_char() from main() and introduce pseudo-instructions asm_get_char() and asm_put_char() to exercise our memory-mapped I/O][:asm :"input handling" :peripheral]
[44:18][Add asm_getchar() and asm_putchar() calls in main()][:asm :"input handling" :peripheral]
[44:45][:Run the simulator to see its infinite output][:asm :"input handling" :peripheral]
[45:02][Call get_char() in the main loop][:asm :"input handling" :peripheral]
[45:08][:Run it, press 'x' and see X5 get populated with 120][:asm :"input handling" :peripheral]
[45:33][Remove both getchar() and print_hart_state() from the main loop, and add a repeat label and asm_j() to our assembly][:asm :"input handling" :peripheral]
[46:37][:Run it to try our echo-loop][:asm :"input handling" :peripheral]
[46:48][A few words on our memory-mapped I/O, with a mention of mame[ref
    site=GitHub
    page="mamedev / mame"
    url=https://github.com/mamedev/mame] and the Sega X Board[ref
        site="Sega Retro"
        page="Sega X Board"
        url=https://segaretro.org/Sega_X_Board]][:asm :"input handling" :peripheral :speech]
[54:46][Consider moving on to doing an RPN (Reverse Polish notation) to RISC-V code generator][:asm :"code generation" :speech]
[56:46][RPN to RISC-V :"code generation"][:asm :speech]
[58:06][Introduce gen_rpn() (and necessary functions) as an RPN to RISC-V code generator][:asm :"code generation"]
[1:18:30][Try out our gen_rpn()][:asm :"code generation"]
[1:20:11][Step through gen_rpn() to see what it does][:asm :"code generation" :run]
[1:22:25][Print out the registers in the main loop][:asm]
[1:22:31][:Run it to follow what gen_rpn() does][:asm :"code generation"]
[1:24:47][Enable gen_rpn() to push the correct decimal values of our ASCII characters][:asm :"code generation"]
[1:27:21][:Run it to see that it pushes the correct values][:asm :"code generation"]
[1:27:44][Try to make gen_rpn() generate the code for a +2][:asm :"code generation"]
[1:28:01][:Run it to see that it computes it correctly, but prints out an extra character][:asm :"code generation"]
[1:29:09][Make bus_load_word() eat '\\n'][:asm :"code generation"]
[1:30:00][:Run it to see that it looks good][:asm :"code generation"]
[1:30:26][Make gen_rpn() insert '\\n' after each digit][:asm :"code generation"]
[1:31:12][:Run it to see that nicer printout][:asm :"code generation"]
[1:31:16][Introduce a duplication character in gen_rpn()][:asm :"code generation"]
[1:31:59][:Run it to see how that works][:asm :"code generation"]
[1:32:13][Reflect on our RPN to RISC-V generator][:asm :"code generation" :speech]
[1:32:57][Try to make gen_rpn() calculate the digit-wise complement][:asm :"code generation"]
[1:33:22][:Run it to see that it works][:asm :"code generation"]
[1:33:32][That's it for today, and likely also next week to write articles][:speech]
[/video]