diff options
| author | Jacques Comeaux <jacquesrcomeaux@protonmail.com> | 2024-05-29 08:15:09 -0500 |
|---|---|---|
| committer | Jacques Comeaux <jacquesrcomeaux@protonmail.com> | 2024-05-29 08:15:09 -0500 |
| commit | 86b72b11d6abcc602a93aa480f27644cc0b34373 (patch) | |
| tree | 5c1c7875e9ae3cc72248d5e7dab9af083de98d6d /assembler/uart.s | |
| parent | e8bc3587cce27b25ba07469964828a327471e5ed (diff) | |
Use absolute branches for subroutine calls
Diffstat (limited to 'assembler/uart.s')
| -rw-r--r-- | assembler/uart.s | 107 |
1 files changed, 55 insertions, 52 deletions
diff --git a/assembler/uart.s b/assembler/uart.s index b845c8b..8dd6a68 100644 --- a/assembler/uart.s +++ b/assembler/uart.s @@ -7,59 +7,62 @@ .equ UARTFR_OFST, 0x18 .type uart_send, %function -.global uart_send - -uart_send: - ldr r1, =UART0_BASE - movs r3, 0b1 << 5 // TX FIFO full -1: - ldr r2, [r1, UARTFR_OFST] - tst r2, r3 - bne 1b - strb r0, [r1, UARTDR_OFST] - bx lr - .type uart_recv, %function -.global uart_recv - -uart_recv: - ldr r1, =UART0_BASE - movs r3, 0b1 << 4 // RX FIFO empty -1: - ldr r2, [r1, UARTFR_OFST] - tst r2, r3 - bne 1b - ldrb r0, [r1, UARTDR_OFST] - bx lr - +.type get_char, %function .type send_hex, %function + +.global uart_send +.global uart_recv +.global get_char .global send_hex -send_hex: - push {lr} - movs r4, r0 - movs r0, '0 - bl uart_send - movs r0, 'x - bl uart_send - movs r5, 8 // eight nibbles in a word -0: - movs r0, 28 // rotate left 4 - rors r4, r0 - movs r0, 0xF // lowest nibble mask - ands r0, r4 - cmp r0, 0x9 // number or letter? - bhi 1f - adds r0, '0 - b 2f -1: - adds r0, ('A - 0xA) -2: - bl uart_send - subs r5, 1 - bne 0b - movs r0, '\r - bl uart_send - movs r0, '\n - bl uart_send - pop {pc} +uart_send: LDR R1, =UART0_BASE // 0x0000 0x4917 + MOVS R3, 0b1 << 5 // 0x0002 0x2320 ; TX FIFO FULL +1: LDR R2, [R1, UARTFR_OFST] // 0x0004 0x670A + TST R2, R3 // 0x0006 0x421A + BNE 1b // 0x0008 0xD1FC + STRB R0, [R1, UARTDR_OFST] // 0x000A 0x7008 + BX LR // 0x000C 0x4770 +uart_recv: LDR R1, =UART0_BASE // 0x000E 0x4914 + MOVS R3, 0b1 << 4 // 0x0010 0x2310 ; RX FIFO EMPTY +1: LDR R2, [R1, UARTFR_OFST] // 0x0012 0x670A + TST R2, R3 // 0x0014 0x421A + BNE 1b // 0x0016 0xF1FC + LDRB R0, [R1, UARTDR_OFST] // 0x0018 0x7808 + BX LR // 0x001A 0x4770 +get_char: PUSH {LR} // 0x001C 0xB500 + BL uart_recv // 0x001E 0xF7FF + // 0x0020 0xFFF6 + CMP R0, R8 // 0x0022 0x4540 + POP {PC} // 0x0024 0xBD00 +send_hex: PUSH {LR} // 0x0026 0xB500 + MOVS R4, R0 // 0x0028 0x0004 + MOVS R0, '0 // 0x002A 0x2030 + BL uart_send // 0x002C 0xF7FF + // 0x002E 0xFFE8 + MOVS R0, 'x // 0x0030 0x2078 + BL uart_send // 0x0032 0xF7FF + // 0x0034 0xFFE5 + MOVS R5, 8 // 0x0036 0x2508 ; EIGHT NIBBLES IN A WORD +0: MOVS R0, 28 // 0x0038 0x201C ; ROTATE LEFT 4 + RORS R4, R0 // 0x003A 0x41C4 + MOVS R0, 0xF // 0x003C 0x200F ; LOWEST NIBBLE MASK + ANDS R0, R4 // 0x003E 0x4020 + CMP R0, 0x9 // 0x0040 0x0000 ; NUMBER OR LETTER? + BHI 1f // 0x0042 0xD801 + ADDS R0, '0 // 0x0044 0x3030 + B 2f // 0x0046 0xE000 +1: ADDS R0, ('A - 0xA) // 0x0048 0x3037 +2: BL uart_send // 0x004A 0xF7FF + // 0x004C 0xFFD9 + SUBS R5, 1 // 0x004E 0x3D01 + BNE 0b // 0x0050 0xD1F9 + MOVS R0, '\r // 0x0052 0x200D + BL uart_send // 0x0054 0xF7FF + // 0x0056 0xFFD4 + MOVS R0, '\n // 0x0058 0x200A + BL uart_send // 0x005A 0xF7FF + // 0x005C 0xFFD1 + POP {PC} // 0x005E 0xBD00 + // 0x0060 0x4000 ; UART0_BASE + // 0x0062 0x4003 |