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[/] [light8080/] [trunk/] [sw/] [demos/] [hello/] [hello.lst] - Rev 78
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0001 0000 ;*******************************************************************************0002 0000 ; tb1.asm -- light8080 core basic demo: 'Hello World!"0003 0000 ;*******************************************************************************0004 0000 ; Should be used with SoC vhdl\soc\l80soc.vhdl0005 0000 ; Assembler format compatible with TASM for DOS and Linux.0006 0000 ;*******************************************************************************0007 0000 ; This program will print a Hello message to a 9600/8/N/1 serial port, then0008 0000 ; will loop forever copying the input port P1 to the output port P2.0009 0000 ; This demo is meant to be used as a starting point for those wanting to play0010 0000 ; with the l80soc core -- which in turn is little more than an usage example0011 0000 ; for the light8080 cpu core.0012 0000 ; See the readme file for instructions for setting up a project with this0013 0000 ; program on Digilentic's DE-1 development board.0014 0000 ;*******************************************************************************0015 00000016 0000 ; DS pseudo-directive; reserve space in bytes, without initializing it0017 0000 #define ds(n) \.org $+n0018 00000019 0000 MASK_RX_IRQ: .equ 20h0020 0000 MASK_TX_IRQ: .equ 10h0021 0000 MASK_RX_RDY: .equ 02h0022 0000 MASK_TX_RDY: .equ 01h0023 00000024 0000 UART_DATA: .equ 80h0025 0000 UART_STATUS: .equ 81h0026 0000 UART_BAUDL: .equ 82h0027 0000 UART_BAUDH: .equ 83h0028 0000 IRQ_ENABLE: .equ 88h0029 00000030 0000 P1IN: .equ 84h0031 0000 P2OUT: .equ 86h0032 00000033 00000034 0000 ;*******************************************************************************0035 00000036 0000 .org 0H ; Reset entry point0037 0000 C3 60 00 jmp start ; Skip the rst address area0038 00030039 0003 ;***** Interrupt vectors in area 0008h-0038h *****************0040 00030041 0008 .org 0h+(1*8) ; interrupt vector 10042 0008 C9 ret0043 0010 .org 0h+(2*8) ; interrupt vector 20044 0010 C9 ret0045 0018 .org 0h+(3*8) ; interrupt vector 30046 0018 C9 ret0047 0020 .org 0h+(4*8) ; interrupt vector 40048 0020 C9 ret0049 0028 .org 0h+(5*8) ; interrupt vector 50050 0028 C9 ret0051 0030 .org 0h+(6*8) ; interrupt vector 60052 0030 C9 ret0053 00310054 0038 .org 0h+(7*8) ; interrupt vector 70055 0038 C3 A7 00 int38h: jmp irq_uart ; UART interrupt0056 003B0057 003B ;***** program entry point *******************************************0058 003B0059 0060 start: .org 60H0060 0060 31 50 01 lxi sp,stack0061 00630062 0063 ; Initialize UART RX and TX buffers0063 0063 21 EB 00 lxi h,void_buffer0064 0066 22 EC 00 shld ptr_tx0065 0069 21 F0 00 lxi h,rx_buffer0066 006C 22 EE 00 shld ptr_rx0067 006F ; Set up UART baud rate to 9600 bauds @ 50MHz:0068 006F ; (50E6 / 9600) = 5208d = 1458h0069 006F 3E 14 mvi a,14h0070 0071 D3 83 out UART_BAUDH0071 0073 3E 58 mvi a,58h0072 0075 D3 82 out UART_BAUDL0073 00770074 0077 ; Clear P2 port0075 0077 3E 00 mvi a,00h0076 0079 D3 86 out P2OUT0077 007B0078 007B ; Set up interrupts0079 007B 3E 08 mvi a,08h ; Enable UART irq...0080 007D D3 88 out IRQ_ENABLE0081 007F FB ei ; ...and enable interrupts in the CPU0082 00800083 0080 ; print hello message to console0084 0080 21 96 00 lxi h,msg_hello0085 0083 CD DE 00 call print_string0086 00860087 0086 forever:0088 0086 DB 84 in P1IN0089 0088 4F mov c,a0090 0089 07 rlc0091 008A 07 rlc0092 008B 81 add c0093 008C D3 86 out P2OUT0094 008E C3 86 00 jmp forever0095 00910096 0091 F3 di0097 0092 76 hlt0098 0093 C3 93 00 done: jmp done0099 00960100 0096 0A 0D 0A 48 msg_hello: .text "\n\r\nHello World!$\000"0100 009A 65 6C 6C 6F0100 009E 20 57 6F 720100 00A2 6C 64 21 240100 00A6 000101 00A70102 00A7 ;irq_uart: UART interrupt processing0103 00A7 irq_uart:0104 00A7 E5 push h0105 00A8 F5 push psw0106 00A90107 00A9 ; Deal with RX interrupt (if any) first and then the TX interrupt.0108 00A9 DB 81 in UART_STATUS ; Is there new data in the RX register?0109 00AB E6 20 ani MASK_RX_IRQ0110 00AD CA C0 00 jz irq_uart_rx_done ; If there isn't, process TX interrupt.0111 00B00112 00B0 ; Process UART RX interrupt0113 00B0 irq_uart_rx:0114 00B0 3E 20 mvi a,MASK_RX_IRQ ; Clear IRQ flag.0115 00B2 D3 81 out UART_STATUS0116 00B4 DB 80 in UART_DATA ; Get RX byte...0117 00B6 D3 86 out P2OUT ; ...display it in the output port...0118 00B8 2A EE 00 lhld ptr_rx ; ...and store it in the rx buffer.0119 00BB 77 mov m,a0120 00BC 23 inx h0121 00BD 22 EE 00 shld ptr_rx ; Update the rx buffer pointer.0122 00C0 ; Note there's no check for RX buffer overrun!0123 00C00124 00C0 irq_uart_rx_done:0125 00C0 ; Ok, RX is done. Now deal with TX irq, if any0126 00C0 DB 81 in UART_STATUS ; Is the TX buffer re new data in the RX register?0127 00C2 E6 10 ani MASK_TX_IRQ0128 00C4 CA DA 00 jz irq_uart_end ; If there isn't, we're done.0129 00C70130 00C7 ; process UART TX interrupt0131 00C7 irq_uart_tx:0132 00C7 3E 10 mvi a,MASK_TX_IRQ ; Clear IRQ flag.0133 00C9 D3 81 out UART_STATUS0134 00CB 2A EC 00 lhld ptr_tx ; Get next byte from the TX buffer0135 00CE 7E mov a,m0136 00CF FE 24 cpi '$' ; Did we reach the end of the buffer?0137 00D1 CA DA 00 jz irq_uart_tx_done ; If we did, we're done here...0138 00D4 23 inx h ; ...otherwise increment the TX pointer...0139 00D5 22 EC 00 shld ptr_tx0140 00D8 D3 80 out UART_DATA ; ...and transmit the data byte.0141 00DA0142 00DA irq_uart_tx_done:0143 00DA0144 00DA irq_uart_end:0145 00DA F1 pop psw ; Done, quit.0146 00DB E1 pop h0147 00DC FB ei0148 00DD C9 ret0149 00DE ; Note there's no check for RX buffer overrun! we shouldn't need it0150 00DE ; in this program, anyway.0151 00DE0152 00DE0153 00DE ;print_string: print $-terminated string at HL0154 00DE ; Returns as soon as the transmission has started; transmission proceeds in0155 00DE ; 'background' through the UART interrupt service routine.0156 00DE print_string:0157 00DE ; We don't check if there's a transmission going on, we just start0158 00DE ; transmitting. Not suitable for real use!0159 00DE 7E mov a,m ; Get first character from string...0160 00DF 23 inx h ; ...and move updated string pointer to TX0161 00E0 22 EC 00 shld ptr_tx ; buffer pointer.0162 00E3 FE 24 cpi '$' ; Kickstart transmission by sending 1st byte...0163 00E5 CA EA 00 jz print_string_end; ...unless its the end of string marker.0164 00E8 D3 80 out UART_DATA ;0165 00EA print_string_end:0166 00EA C9 ret0167 00EB0168 00EB0169 00EB ; data space, placed immediately after object code in memory0170 00EB 24 void_buffer: .text "$"0171 00EC ptr_tx: ds(2)0171 00EE0172 00EE ptr_rx: ds(2)0172 00F00173 00F0 rx_buffer: ds(32)0173 01100174 0110 ds(64)0174 01500175 0150 stack: ds(2)0175 01520176 0152 .end0177 0152 tasm: Number of errors = 0
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