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--- en:pfw:assemblers_rp2040-assembler [2023-09-04 18:11] – gelöscht - Externe Bearbeitung (Unbekanntes Datum) 127.0.0.1
+++ en:pfw:assemblers_rp2040-assembler [2023-10-02 17:04] (current) – [Two usage examples] willem
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+{{pfw:banner.png}}
+====== Assembler for RP2040 ======
+===== The idea =====
+A compact Forth-style macro assembler with an efficient literal pool mechanism for the RP2040.\\
+A Forth-style assembler uses all the capabilities of the Forth interpreter and assembles opcodes in between.\\
+An example:
+<code>
+code SQUARED    ( +n -- +n^2 )
+    tos tos muls,  next,
+end-code
+</code>
+===== Implementation =====
+The example code asumes a 32-bit machine that has 16-bit & 32-bit compile actions.
+It is also asumed that the code runs in RAM as noForth T on the RP2040 does.
+Because the Thumb-2 opcodes of the ARMv6-M use a RISC like architecture, macros
+are added to make assembly a bit more easy.
+An implementation example for ''%%CODE%%'' and ''%%END-CODE%%'' is showed too. Missing words in Generic Forth are:
+<code forth>
+(*          ( "ccc" -- )        - Skip all text until *) is found
++TO         ( n "name" -- )     - Add n to the contents of the value "name"
+VOCABULARY  ( "name" -- )       - Define a named wordlist
+</code>
+==== All Thumb2 instructions ====
+<code forth>
+✦ Two low register opcodes
+    ands,       eors,       adcs,       sbcs,       rors,       tst,
+    neg,        cmn,        orrs,       muls,       bics,       mvns,
+    sxth,       sxtb,       uxth,       uxtb,       rev,        rev16,
+    revsh,      lsls,       lsrs,       asrs,       movs,       cmp,
+✦  Two all register opcodes
+    add,        mov,        cmp,
+✦ Three low register opcodes
+    adds,       subs,       str,        strb,       strh,       ldrb,
+    ldrh,       ldr,        ldrsb,      ldrsh,
+✦ Two low register & 3-bits immediate
+    adds,       subs,       rsbs,
+✦ Two low register & 5-bits immediate
+    lsls,       lsrs,       asrs,       str,        strb,       strh,
+    ldr,        ldrb,       ldrh,
+✦ One low register & 7-bits immediate (RP-specific)
+    add,        subs,       sub,
+✦ One low register & 8-bits immediate
+    movs,       cmp,        str, (rp)   ldr, (rp)   ldr,        add, (rp)
+    push,       pop,        bkpt,       udf,        svc,        adr,
+    stm,        ldm,        adds,       subs,
+✦ Various 16-bit opcodes
+    noop,       nop,        yield,      wfe,        wfi,        sev,
+    cpsie,      cpsid,      bx,         blx,
+✦ Fourteen jump instructions
+    =?          cs?         neg?        vs?         u>?         <?
+    >?          no
+✦ Control structures
+    if,         else,       then,       ahead,
+    begin,      while,      repeat,     again,      until,
+✦ Literal pool additions
+    ALIGN,      CODE>       POOL,       APOOL,      ##
+✦ Assembler macros
+    ALIGN,      ##          POOL,       APOOL,      )+
+    -)          NEXT,
+</code>
+==== Two usage examples ====
+<code>
+code LSHIFT ( x1 +n -- x2 )
+    day tos movs,       \ 1 - +n to DAY
+    tos  sp )+ ldr,     \ 2 - pop X1 to TOS
+    tos day lsls,       \ 1 - Shift TOS DAY positions left
+    next,               \ 6
+end-code
+code KEY?)  ( -- f )
+    40034018 ,          \ UART0 UARTFR
+code>
+    sun  w ) ldr,       \ Read UARTFR to SUN
+    tos  sp -) str,     \ Push stack
+    tos  sun ) ldr,     \ Read flags
+    tos 1B # lsls,      \ Build flag out of bit-4
+    tos 1F # asrs,      \ Extend sign
+    tos tos mvns,       \ Invert flag
+    next,
+end-code
+</code>
+<code></code>
+| File name | Purpose | in Dropbox (external link) |
+| [[https://www.dropbox.com/s/glvdl0runl65u3t/Thumb%20assembler%20doc%20v2.pdf?dl=1|Thumb assembler doc v2.pdf]] | Documentation | [[https://www.dropbox.com/s/glvdl0runl65u3t/Thumb%20assembler%20doc%20v2.pdf?dl=0|Assembler documentation]] |
+| [[https://www.dropbox.com/s/jaw8dalna8sodut/RP2040-asm%20uni.f?dl=0|RP2040-asm uni.f]] | RP2040 assembler | [[https://www.dropbox.com/s/0ubyr344j7a1q7k/noForth-T-das.f?dl=0|noForth RP2040 assembler]] |
+| [[https://www.dropbox.com/s/2g4glx7gcnmuvyl/RP2040-asm-extensions%20uni.f?dl=0|RP2040-asm-extensions uni.f]] | RP2040 ass. extensions | [[https://www.dropbox.com/scl/fi/65wbh85v95rvh4uoo5rtd/T-asm-ext.f?rlkey=v8cpj3mr45oz9ou4v3apyi5w2&dl=0|noForth assembler ext.f]] |
+==== Contributions ====
+<html><h2 style="background-color:yellow">Alternative Implementations</h2></html>
+[[en:pfw:welcome|Back to PFW page]]