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/forwardcom/examples/calculator.as
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/**************************** calculator.as ********************************* |
* Author: Agner Fog |
* date created: 2021-05-26 |
* last modified: 2021-07-20 |
* Version: 1.11 |
* Project: ForwardCom example, assembly code |
* Description: Simple test of arithmetic instructions |
* Link with libc_light.li |
* |
* Copyright 2021 GNU General Public License http://www.gnu.org/licenses |
*****************************************************************************/ |
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// Library functions in libc_light.li |
extern _print_string: function reguse=3,0 |
extern _printf: function reguse=0xF,0 |
extern _gets_s: function reguse=3,0 |
extern _atoi: function reguse=3,0 |
extern _multiply_int: function reguse=1,0 |
extern _divide_int: function reguse=3,0 |
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%serial_input_status = 9 // serial input status port |
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const section read ip // read-only data section |
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// text strings |
int8 text1 = "\nSimple calculator with two integers, a and b\n\nEnter a: \0" |
int8 text2 = "\nEnter b: \0" |
int8 text3 = "\nAgain (y/n)?: \0" |
int8 text4 = "\nGoodbye\n\0" |
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// format string for printf |
int8 formatstring = "\n\na = %8i" |
int8 "\nb = %8i" |
int8 "\na + b = %8i" |
int8 "\na - b = %8i" |
int8 "\na * b = %8i" |
int8 "\na / b = %8i" |
int8 "\na %% b = %8i\n\0" |
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const end |
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code section execute // code section |
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_main function public // program start |
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%stackframe = 64 // size of local data |
int64 sp -= stackframe // allocate input buffer on stack |
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do { // repeat as long as user answers yes |
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int r0 = 1 // clear input buffer |
int output(r0, r0, serial_input_status) |
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int64 r0 = address([text1]) |
call _print_string // print intro text |
int64 r0 = sp |
int r1 = stackframe // max. size of input buffer |
call _gets_s // read a as string |
call _atoi // convert to integer |
int32 r8 = r0 // save a |
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int64 r0 = address([text2]) |
call _print_string // print Enter b |
int64 r0 = sp |
int r1 = stackframe // max. size of input buffer |
call _gets_s // read b as string |
call _atoi // convert to integer |
int32 r9 = r0 // save b |
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// set up parameter list with results |
// (reuse the input buffer as parameter list) |
int32 [sp+0x00] = r8 // a |
int32 [sp+0x08] = r9 // b |
int32 r2 = r8 + r9 // a + b |
int32 [sp+0x10] = r2 |
int32 r2 = r8 - r9 // a - b |
int32 [sp+0x18] = r2 |
int32 r0 = r8 |
int32 r1 = r9 |
call _multiply_int // a * b, using function call |
int32 [sp+0x20] = r0 |
int32 r0 = r8 |
int32 r1 = r9 |
call _divide_int // a / b, using function call |
int32 [sp+0x28] = r0 |
int32 [sp+0x30] = r1 // a % b |
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// print results |
int64 r0 = address([formatstring]) // pointer to format string |
int64 r1 = sp // pointer to parameter list |
call _printf // print results |
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// ask if the user wants to try again |
int64 r0 = address([text3]) |
call _print_string // print Again? |
int64 r0 = sp |
int r1 = stackframe // max. size of input buffer |
call _gets_s // read answer as string |
int8 r1 = [sp] | 0x20 // read first character of answer, convert to lower case |
} while (int8+ r1 == 'y') // repeat if user enters 'y' |
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// write goodbye text |
int64 r0 = address([text4]) |
call _print_string // print goodbye |
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int64 sp += stackframe // release stack frame |
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int r0 = 0 |
return // return from main |
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_main end |
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code end |