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hardwired jump table

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This makes the microcontroller very application dependent,
but may save use some headaches.
The idea is to write a program to produce the code to show a
complex drawing.
This commit is contained in:
giomba 2021-08-10 09:26:51 +02:00
parent 53da6b7171
commit 5bb884c502
2 changed files with 324 additions and 45 deletions
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336
main.S
View File

@ -35,12 +35,14 @@ main:
ldi r16, 1
sts line, r16
; r0 always holds 0
clr r0
call setup_c
sei ; global interrupt enable
1:
call loop_c
rjmp 1b
.global int_horizontal_sync
@ -57,9 +59,10 @@ int_horizontal_sync: ; +3
sts line, r30 ; +18
sts line + 1, r31 ; +20
cpi r31, 0 ; +21
brne enter ; +22, +23
cpi r30, VERTICAL_OFFSET ; +23
brlo int_horizontal_sync_end ; +24
breq enter ; +23
jmp int_horizontal_sync_end
# cpi r30, VERTICAL_OFFSET ; +23
# brlo int_horizontal_sync_end ; +24
enter:
; here, +23 or +24 cycles have passed since horizontal sync
@ -97,16 +100,29 @@ int_timer_0:
andi r31, 0xfd ; mask disable interrupt timer A
sts TIMSK0, r31
; draw things
ldi r30, lo8(line_buffer)
ldi r31, hi8(line_buffer)
clr r0
ldi zl, pm_lo8(line_jump_table)
ldi zh, pm_hi8(line_jump_table)
.rept LINE_BUFFER_SIZE
ld r29, z+
out IO(PORTB), r29
nop
.endr
lds r29, line
add zl, r29
adc zh, r0
add zl, r29
adc zh, r0
ijmp
# ; draw things
# ldi r30, lo8(line_buffer)
# ldi r31, hi8(line_buffer)
#.rept LINE_BUFFER_SIZE
# ld r29, z+
# out IO(PORTB), r29
# nop
#.endr
jump_table_return_address:
pop r29
pop r30
pop r31
@ -139,4 +155,300 @@ int_vertical_sync_end:
pop r31
reti
.global line_0
line_0:
.rept 200
nop
.endr
sbi IO(PORTB), 4
nop
nop
nop
nop
cbi IO(PORTB), 4
.rept 50
nop
.endr
sbi IO(PORTB), 4
nop
nop
nop
nop
cbi IO(PORTB), 4
jmp jump_table_return_address
.global line_1
line_1:
.rept 50
nop
.endr
sbi IO(PORTB), 4
nop
nop
cbi IO(PORTB), 4
jmp jump_table_return_address
line_jump_table:
jmp line_0
jmp line_0
jmp line_0
jmp line_0
jmp line_0
jmp line_0
jmp line_0
jmp line_0
jmp line_0
jmp line_0
jmp line_0
jmp line_0
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jmp line_1
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33
main.c
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@ -18,38 +18,5 @@ ISR(TIMER0_COMPA_vect, ISR_NAKED) {
}
void setup_c() {
/*
for (int i = 0; i < LINE_BUFFER_SIZE; ++i) {
line_buffer[i] = (i % 2) ? 0x0 : 0xff;
}
*/
}
void loop_c() {
for (;;) {
const int current_line = line;
switch (current_line) {
case 76: case 134: memcpy(line_buffer, "AAAAAAAAAAAAAAAAAAAAAA", 22); break;
case 80: memcpy(line_buffer, "11111111AAAA1111111111", 22); break;
case 84: memcpy(line_buffer, "111111111AAA1111111111", 22); break;
case 88: case 98: memcpy(line_buffer, "11AAAAA111AA11AAAAAAAA", 22); break;
case 92: memcpy(line_buffer, "11AAAAAA11AA11AAAAAAAA", 22); break;
case 102: memcpy(line_buffer, "111111111AAA11111111AA", 22); break;
case 106: memcpy(line_buffer, "11111111AAAA11111111AA", 22); break;
case 110: memcpy(line_buffer, "11A111AAAAAA11AAAAAAAA", 22); break;
case 114: memcpy(line_buffer, "11AA111AAAAA11AAAAAAAA", 22); break;
case 118: memcpy(line_buffer, "11AAA111AAAA11AAAAAAAA", 22); break;
case 122: memcpy(line_buffer, "11AAAA111AAA11AAAAAAAA", 22); break;
case 126: memcpy(line_buffer, "11AAAAA111AA1111111111", 22); break;
case 130: memcpy(line_buffer, "11AAAAAA11AA1111111111", 22); break;
}
line_buffer[60] = (current_line > 50 && current_line < 100) ? WHITE : BLACK;
if (current_line > 200 && current_line % 8 == 0) {
const uint8_t current_number = frame >> 2;
for (uint8_t i = 0; i < 8; ++i) {
line_buffer[i] = ((current_number >> i) & 0x1) ? WHITE : BLACK;
}
}
}
}