mdw@git.distorted.org.uk Git - ssr/blob - StraySrc/Libraries/Sapphire/sail/sh/express

   1 ;
   2 ; express.sh
   3 ;
   4 ; Evaluation of BASIC expressions
   5 ;
   6 ; © 1995 Straylight
   7 ;
   8
   9 ;----- Overview -------------------------------------------------------------
  10 ;
  11 ; Functions provided:
  12 ;
  13 ;  express_pop
  14 ;  express_popTwo
  15 ;  express_push
  16 ;  express_fnCont
  17 ;  express_read
  18
  19                 [       :LNOT::DEF:express__dfn
  20                 GBLL    express__dfn
  21
  22 ; --- express_pop ---
  23 ;
  24 ; On entry:     --
  25 ;
  26 ; On exit:      R0,R1 == value popped off
  27 ;
  28 ; Use:          Pops a value from the stack.
  29
  30                 IMPORT  express_pop
  31
  32 ; --- express_popTwo ---
  33 ;
  34 ; On entry:     --
  35 ;
  36 ; On exit:      R0-R3 == two values popped from the stack
  37 ;
  38 ; Use:          Pops two values from the stack.
  39
  40                 IMPORT  express_popTwo
  41
  42 ; --- express_push ---
  43 ;
  44 ; On entry:     R0,R1 == l/rvalue to push
  45 ;
  46 ; On exit:      --
  47 ;
  48 ; Use:          Pushes a value onto the expression stack.
  49
  50                 IMPORT  express_push
  51
  52 ; --- express_fnCont ---
  53 ;
  54 ; On entry:     Involved
  55 ;
  56 ; On exit:      Similarly involved.
  57 ;
  58 ; Use:          We continue here after executing a function.
  59
  60                 IMPORT  express_fnCont
  61
  62 ; --- express_read ---
  63 ;
  64 ; On entry:     R0 == 1 to read an lvalue, 2 to read ident, 0 otherwise
  65 ;               R7, R8, R9 == lookahead token
  66 ;               R10 == pointer into tokenised buffer
  67 ;               R11 == evaluation stack pointer
  68 ;               R12 == anchor pointer
  69 ;
  70 ; On exit:      R0,R1 == value of expression
  71 ;               R7, R8, R9 == lookahead token
  72 ;               R0, R1 == result of expression
  73 ;               R10 == moved on to first char after expression
  74 ;
  75 ; Use:          Reads an expression for the current position in the
  76 ;               tokenised file.
  77
  78                 IMPORT  express_read
  79
  80                 ]
  81
  82 ;----- That's all, folks ----------------------------------------------------
  83
  84                 END