-.define begdat, begbss
-.define hol0, argv, envp, reghp
-.define ignmask, trpreg, rcktrap
+! head_em.s
+.define begdat,begbss,hol0,argv,envp,_RegHp,_incptflag
+.define _Lineno,_Filna,_IgnoreMask,_TrpReg
-.sect .text
-.sect .rom
-.sect .data
-.sect .bss
-
-.sect .text
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
- ADR R0,begbss
- ADR R1,_endbss
- MOV R2,#0
+.sect .text
+.base 0x8000
+ ADR R0,begbss
+ ADR R1,_endbss
+ MOV R2,#0
+ ADR R3,_incptflag
+ STR R2,[R3]
1:
- STR R2,[R0],#4
- CMP R0,R1
- BGT 1b
-
- MOV R12, #0x100000
- ADR R11, envp
- STMFD R12<, {R11}
- ADR R11, argv
- STMFD R12<, {R11}
- MOV R11, #1
- STMFD R12<, {R11}
- BAL.L _m_a_i_n
-rcktrap:
- SWI 1
+ STR R2,[R0],#4
+ CMP R0,R1
+ BLT 1B
+! the next 2 lines are OS specific:
+ SWI 16 ! OS_Getenv
+ SUB R12, R1, #8 ! Get end of ram
+! R0 points to command string
+! (argv,argc) code for C
+! or Pascal file names
+ MOV R9,R0 ! save pt in R0
+ MOV R8,#0 ! string length
+len:
+ LDR.B R7,[R9],#1
+ CMP R7,#0
+ ADD.NE R8,R8,#1
+ BNE len
+ MOV R7,R8 ! save len in R7
+! round up to multiple of 4
+ ADD R8,R8,#4
+ MVN R6, #3 !FFFFFFFC
+ AND R8,R8,R6
+! make room on stack
+ SUB R12,R12,R8 ! word aligned
+! now determine argc
+! OS intercepts blank lines, so
+! there must be at least one arg
+ MOV R9,R0
+ MOV R6,#0 ! holds argc
+ MOV R5,#0 ! char count
+loop1:
+ CMP R5,R7
+ BGT next1
+ LDR.B R4,[R9],#1
+ ADD R5,R5,#1
+ CMP R4,#32
+ BEQ loop1 !skip spaces
+ ADD R6,R6,#1 ! new arg
+nospace1:
+ CMP R5,R7
+ BGT next1
+ LDR.B R4,[R9],#1
+ ADD R5,R5,#1
+ CMP R4,#32
+ BNE nospace1
+ CMP R5,R7
+ BCC loop1
+! BEQ loop1
+next1:
+! store argc
+ ADR R5,argc
+ STR R6,[R5]
+! copy the string
+! onto the stack
+ MOV R9,R0 !source
+ MOV R2,R12 !dest
+ MOV R3,R7 !#chars
+loop2:
+ LDR.B R4,[R9],#1
+ STR.B R4,[R2],#1
+ SUB.S R3,R3,#1
+ BNE loop2
+ MOV R4, #0 ! zero terminator
+ STR.B R4,[R2]
+! create space on the stack for
+! the pointers to individual args
+ MOV R11, R12 ! string pt
+ MOV R8,R6,LSL #2
+ SUB R12,R12,R8
+! save pointer to argv[0]
+ ADR R1,argv
+ STR R12,[R1]
+! determine argv[0] .. argv[argc-1]
+! and store on stack
+! R11 = start of string
+! R7 = string lenth
+! R12 = stack pointer
+! R6 = argc
+ MOV R9, #0 !char count
+ MOV R8, #0 !arg count
+ MOV R5,R11
+loop3:
+ CMP R9,R7
+ BGT next2
+ LDR.B R4,[R5],#1
+ ADD R9,R9,#1
+ CMP R4,#32
+ BEQ loop3
+ CMP R9,R7
+ BGT next2
+ SUB R4,R5,#1 !compensate for incr
+ STR R4,[R12,R8,LSL #2]
+ ADD R8,R8,#1
+nospace2:
+ CMP R9,R7
+ BGT next2
+ LDR.B R4,[R5],#1
+ ADD R9,R9,#1
+ CMP R4,#32
+ BNE nospace2
+ CMP R9,R7
+ BCC loop3
+! BEQ loop3
+! finally, replace spaces by 0
+next2:
+ MOV R5,R11 !string ptr
+ MOV R6,R7 !string length
+ MOV R3,#0
+loop4:
+ CMP R6,#0
+ BEQ next3
+ LDR.B R4,[R5]
+ CMP R4,#32
+ STR.EQ.B R3,[R5]
+ ADD R5,R5,#1
+ SUB R6,R6,#1
+ BAL loop4
+next3:
+ ADR R11, envp
+ STMFD R12<,{R11}
+ ADR R11,argv
+ LDR R11,[R11]
+ STMFD R12<,{R11}
+ ADR R11, argc
+ LDR R11,[R11]
+ STMFD R12<,{R11}
+ BAL.L _m_a_i_n
+ MOV R11,#0
+ STMFD R12<,{R11}
+ MOV R11,#1
+ STMFD R12<,{R11}
+ BAL.L _EmMon
.sect .bss
begbss:
.sect .data
begdat:
hol0:
- .data4 0
- .data4 0
+ .data4 0
+ .data4 0
argv:
- .data4 2f
+ .data4 0
envp:
- .data4 0
+ .data4 0
+argc:
+.data4 0
2:
- .asciz 'PROGRAM'
-reghp:
- .data4 _endbss
-ignmask:
- .data4 0
-trpreg:
- .data4 0
+ .asciz 'PROGRAM'
+ .align
+_RegHp:
+ .data4 _endbss
+_Lineno:
+ .data4 0
+_Filna:
+ .data4 0
+_IgnoreMask:
+ .data4 0
+_TrpReg:
+ .data4 0
+_incptflag:
+.data4 0
+