| 1 | ! This is the C run-time start-off routine. It's job is to take the
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| 2 | ! arguments as put on the stack by EXEC, and to parse them and set them up the
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| 3 | ! way _main expects them.
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| 4 | ! It also initializes _environ when this variable isn't defined by the
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| 5 | ! programmer. The detection of whether _environ belong to us is rather
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| 6 | ! simplistic. We simply check for some magic value, but there is no other
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| 7 | ! way.
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| 8 |
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| 9 | .extern _main, _exit, crtso, __penviron, __penvp
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| 10 | .extern begtext, begdata, begbss, endtext, enddata, endbss
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| 11 | .text
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| 12 | begtext:
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| 13 | crtso:
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| 14 | xor bp, bp ! clear for backtrace of core files
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| 15 | mov bx, sp
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| 16 | mov ax, (bx) ! argc
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| 17 | lea dx, 2(bx) ! argv
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| 18 | lea cx, 4(bx)
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| 19 | add cx, ax
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| 20 | add cx, ax ! envp
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| 21 |
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| 22 | ! Test if environ is in the initialized data area and is set to our
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| 23 | ! magic number. If so then it is not redefined by the user.
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| 24 | mov bx, #_environ
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| 25 | cmp bx, #__edata ! within initialized data?
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| 26 | jae 0f
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| 27 | testb bl, #1 ! aligned?
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| 28 | jnz 0f
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| 29 | cmp (bx), #0x5353 ! is it our environ?
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| 30 | jne 0f
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| 31 | mov __penviron, bx ! _penviron = &environ;
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| 32 | 0: mov bx, __penviron
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| 33 | mov (bx), cx ! *_penviron = envp;
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| 34 |
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| 35 | push cx ! push envp
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| 36 | push dx ! push argv
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| 37 | push ax ! push argc
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| 38 |
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| 39 | call _main ! main(argc, argv, envp)
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| 40 |
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| 41 | push ax ! push exit status
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| 42 | call _exit
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| 43 |
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| 44 | hlt ! force a trap if exit fails
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| 45 |
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| 46 | .data
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| 47 | begdata:
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| 48 | .data2 0 ! for sep I&D: *NULL == 0
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| 49 | __penviron:
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| 50 | .data2 __penvp ! Pointer to environ, or hidden pointer
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| 51 |
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| 52 | .bss
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| 53 | begbss:
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| 54 | .comm __penvp, 2 ! Hidden environment vector
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