diff options
| -rw-r--r-- | interpret.e | 76 | ||||
| -rw-r--r-- | quine.asm | 35 |
2 files changed, 96 insertions, 15 deletions
diff --git a/interpret.e b/interpret.e index 2bb9e43..235c98b 100644 --- a/interpret.e +++ b/interpret.e @@ -50,23 +50,83 @@ ." name of latest: " latest @ entry-to-name emitstring newline newline ; -~ TODO this is identical to the flatassembler version, but it needs to fix the -~ conflict with s" +~ Allocate space by incrementing "here", and output a word entry header in +~ it. Also add it to the "latest" linked list. Use zero as the flag values; +~ accept a string pointer on the stack and use its contents as the name. +~ +~ This is the first step of creating a new word. Its responsibility includes +~ everything up to the codeword, not including the codeword; it leaves things +~ all set up to start appending contents to the new word by calling ",". +~ +~ There's a handy diagram of the entry header format under "quick +~ reference", in the description of the exeuction model in evoke.e. Create is +~ responsible for everything up to the codeword, not including it. +~ +~ When a word is created in interpret mode using s" to provide a string +~ literal, the temporary space that s" uses is in the same place as the +~ entry header we're going to write out. It really is very useful to have +~ that work. Fortunately, it does! We're able to avoid needing a special case +~ by doing things in a very careful way, as described below. +~ +~ (string pointer --) : create + ~ We add one to the string length in order to include the trailing null + ~ terminator. This will be the length of our name field; we save an extra + ~ copy of it to help with packing later. + dup stringlen 1 + dup 3unroll + ~ (name field length, string pointer, name field length) + + ~ We use memmove to put the string in its final position, because it works + ~ correctly when the destination overlaps with the source. Notice that we + ~ do this before writing anything else in the entry header, to avoid + ~ stepping on it. The name string always starts ten bytes into the header, + ~ so we can use a fixed offset. + here @ 10 + 3unroll memmove + ~ (name field length) + + ~ Now we can get back to the fields that belong at the start of the entry + ~ header. We take the value of "here" and keep a working copy of it on the + ~ stack, which we'll advance every time we write more bytes. here @ + ~ (name field length, updated "here" pointer) + + ~ Pack the old value of "latest" as the first field of the header, linking + ~ from the newly-defined word to the next-newest word. + ~ + ~ All the entries form a linked list, from newest to oldest. Since the + ~ link is the first field in the entry header, you can get from each entry + ~ to the one before it just by dereferencing the entry pointer. latest @ pack64 + + ~ This is the flags byte. It starts at zero; our caller can change it if + ~ desired. 0 pack8 + + ~ This is the "other" null terminator, used when traversing the name + ~ string backwards for execution-token-to-entry. Yes, the name is + ~ null-terminated at both ends. 0 pack8 - swap packstring + + + ~ The name field is already populated, so just skip past it. + ~ (updated "here" pointer) + + ~ The codeword is aligned to a machine-word boundary, and the padding for + ~ it is create's responsibility. + ~ + ~ By adding the null terminator before adding alignment padding, we've + ~ made sure there's always at least one null byte. Otherwise we'd be missing + ~ the terminator if by chance the name were exactly the wrong length. 8 packalign + ~ (updated "here" pointer) + + ~ Retrieve the value of "here", which still doesn't reflect our additions, + ~ and store it at the adddress of "latest". It's the start of our + ~ newly-defined word, which makes it the latest word. here @ latest ! - here ! ; -latest @ describe -s" foo" create -latest @ describe + ~ Finally, we write our updated value of "here" back into the variable. + here ! ; -~ create 0000001000017fa8 ~ , 0000001000018080 ~ self-codeword 00000010000180d0 ~ variable 0000001000018128 diff --git a/quine.asm b/quine.asm index e86e61c..12a45f8 100644 --- a/quine.asm +++ b/quine.asm @@ -2459,6 +2459,27 @@ cold_start: dq rdx, rsi, mov_reg64_reg64 dq pack_next, lit, 8, packalign, early_here_store + dq litstring, "memmove", early_create, early_self_codeword + dq early_here, fetch + dq rsi, rdx, mov_reg64_reg64 + dq rcx, pop_reg64 + dq rsi, pop_reg64 + dq rdi, pop_reg64 + dq rsi, rax, mov_reg64_reg64 + dq rdi, rax, cmp_reg64_reg64 + dq lit, 4, cc_below, jmp_cc_rel_imm8 + dq rep_movs8 + dq lit, 16, jmp_rel_imm8 + dq rcx, rsi, add_reg64_reg64 + dq rsi, dec_reg64 + dq rcx, rdi, add_reg64_reg64 + dq rdi, dec_reg64 + dq std + dq rep_movs8 + dq cld + dq rdx, rsi, mov_reg64_reg64 + dq pack_next, lit, 8, packalign, early_here_store + dq litstring, "stringlen", early_create, early_self_codeword dq early_here, fetch dq rdi, pop_reg64 @@ -11790,14 +11811,14 @@ defword boot_source, 0x40 ; We'll have logical and real soon now, be patient... :) dq ": is-in-heap dup heap @ <= swap here @ > & ; " - dq ": unlink-pre-heap-words " - dq " latest @ " - dq " dup { dup is-in-heap 0 = { drop exit } if } " - dq " { drop exit } if-else " - dq " { dup @ is-in-heap } { @ } while " - dq " 0 swap ! ; " +; dq ": unlink-pre-heap-words " +; dq " latest @ " +; dq " dup { dup is-in-heap 0 = { drop exit } if } " +; dq " { drop exit } if-else " +; dq " { dup @ is-in-heap } { @ } while " +; dq " 0 swap ! ; " ; Do it immediately, so that we don't accidentally rely on any of that. - dq "unlink-pre-heap-words " + ;dq "unlink-pre-heap-words " ; Now some fancier stack combinators. ; |