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Merge branch 'master' of github.com:cs107e/staff
commit 0bc873476dd0cbf60342cbebe862d04fa75f0f84 Merge: 6c1cd5d 2bde7dc Author: Pat Hanrahan <[email protected]> Date: Fri Feb 1 08:37:00 2019 -0800 Merge branch 'master' of github.com:cs107e/staff
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‎_data/unreleased.csv

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"/lectures/Interrupts2/","Interrupts, cont'd",false
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"/lectures/FloatingPoint/","Floating Point",false
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"/lectures/C-mastery/","C Mastery",false
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"/lectures/Linking/","Modules, Libraries, and Linking",false
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"/lectures/Sound/","Sound",false
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"/lectures/GitWorkflow/","Git Workflow",false
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"/lectures/Sensors/","Sensors",false

‎lectures/Linking/README.md

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---
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released: true
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permalink: /lectures/Linking/
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title: Modules, Libraries, and Linking
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readings: |
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+ Read David Welch's articles on [baremetal programming](https://github.com/dwelch67/raspberrypi/tree/master/baremetal) and [bss data](https://github.com/dwelch67/raspberrypi/tree/master/bssdata).
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---
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‎lectures/Linking/code/blink-cs107e/Makefile

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APPLICATION = blink
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MODULES =
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CFLAGS = -Og -Wall -std=c99 -ffreestanding -I$(CS107E)/include
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ASFLAGS = --warn --fatal-warnings
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LDFLAGS = -nostdlib -T memmap -L$(CS107E)/lib
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LDLIBS = -lpi
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all : $(APPLICATION).bin
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%.bin: %.elf
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arm-none-eabi-objcopy $< -O binary $@
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%.elf: %.o $(MODULES) cstart.o start.o
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arm-none-eabi-ld $(LDFLAGS) $^ $(LDLIBS) -o $@
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%.o: %.c
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arm-none-eabi-gcc $(CFLAGS) -c $< -o $@
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%.o: %.s
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arm-none-eabi-as $(ASFLAGS) $< -o $@
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install: $(APPLICATION).bin
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rpi-install.py $<
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clean:
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rm -f *.bin *.elf *.o *.list *~
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.PHONY: all clean install
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.PRECIOUS: %.o %.elf
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# empty recipe used to disable built-in rules for native build
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%:%.c
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%:%.o
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%:%.s

‎lectures/Linking/code/blink-cs107e/READMD.md

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Demonstrates how to link to cs107e libpi

‎lectures/Linking/code/blink-cs107e/blink.c

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#include "gpio.h"
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#include "timer.h"
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void main() {
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gpio_init();
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timer_init();
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gpio_set_function(GPIO_PIN20, GPIO_FUNC_OUTPUT);
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while(1) {
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gpio_write(GPIO_PIN20, 1);
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timer_delay(1);
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gpio_write(GPIO_PIN20, 0);
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timer_delay(1);
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}
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}

‎lectures/Linking/code/blink-cs107e/cstart.c

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// linker memmap places these symbols at start/end of bss
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extern int __bss_start__, __bss_end__;
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extern void main(void);
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// The C function _cstart is called from the assembly in start.s
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// _cstart zeroes out the BSS section and then calls main.
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// After return from main(), turns on the green ACT LED as
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// a sign of successful completion.
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void _cstart(void)
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{
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int *bss = &__bss_start__;
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int *bss_end = &__bss_end__;
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while (bss < bss_end) {
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*bss++ = 0;
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}
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main();
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// Turn on the green ACT LED (GPIO 47)
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volatile unsigned int *GPIO_FSEL4 = (unsigned int *)0x20200010;
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volatile unsigned int *GPIO_SET1 = (unsigned int *)0x20200020;
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*GPIO_FSEL4 = (*GPIO_FSEL4 & ~(7 << 21)) | (1 << 21);
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*GPIO_SET1 = 1 << 15;
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}

‎lectures/Linking/code/blink-cs107e/memmap

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SECTIONS
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{
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.text 0x8000 : { start.o(.text*) *(.text*) }
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.data : { *(.data*) }
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.rodata : { *(.rodata*) }
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__bss_start__ = .;
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.bss : { *(.bss*) *(COMMON) }
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__bss_end__ = ALIGN(8);
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}

‎lectures/Linking/code/blink-cs107e/start.s

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.globl _start
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_start:
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mov sp, #0x8000000
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mov fp, #0
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bl _cstart
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hang: b hang

‎lectures/Linking/code/blink-libpi/Makefile

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APPLICATION = blink
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MODULES = timer.o gpio.o
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CFLAGS = -Og -Wall -std=c99 -ffreestanding
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ASFLAGS = --warn --fatal-warnings
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LDFLAGS = -nostdlib -T memmap
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all : $(APPLICATION).bin
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%.bin: %.elf
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arm-none-eabi-objcopy $< -O binary $@
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%.elf: %.o libpi.a
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arm-none-eabi-ld $(LDFLAGS) $^ -o $@
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libpi.a: $(MODULES) cstart.o start.o
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arm-none-eabi-ar crf $@ $^
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%.o: %.c
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arm-none-eabi-gcc $(CFLAGS) -c $< -o $@
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%.o: %.s
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arm-none-eabi-as $(ASFLAGS) $< -o $@
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install: $(APPLICATION).bin
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rpi-install.py $<
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clean:
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rm -f *.a *.o *.i *.bin *.elf *.list *~ blink.s gpio.s timer.s cstart.s
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.PHONY: all clean install
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.PRECIOUS: %.o %.elf
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# empty recipe used to disable built-in rules for native build
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%:%.c
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%:%.o
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%:%.s

‎lectures/Linking/code/blink-libpi/README.md

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Demonstrates libraries by making libpi.a
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‎lectures/Linking/code/blink-libpi/blink.c

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#include "gpio.h"
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#include "timer.h"
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void main() {
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gpio_init();
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timer_init();
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gpio_set_function(GPIO_PIN20, GPIO_FUNC_OUTPUT);
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while(1) {
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gpio_write(GPIO_PIN20, 1);
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timer_delay(1);
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gpio_write(GPIO_PIN20, 0);
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timer_delay(1);
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}
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}

‎lectures/Linking/code/blink-libpi/cstart.c

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// linker memmap places these symbols at start/end of bss
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extern int __bss_start__, __bss_end__;
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extern void main(void);
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// The C function _cstart is called from the assembly in start.s
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// _cstart zeroes out the BSS section and then calls main.
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// After return from main(), turns on the green ACT LED as
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// a sign of successful completion.
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void _cstart(void)
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{
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int *bss = &__bss_start__;
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int *bss_end = &__bss_end__;
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while (bss < bss_end) {
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*bss++ = 0;
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}
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main();
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// Turn on the green ACT LED (GPIO 47)
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volatile unsigned int *GPIO_FSEL4 = (unsigned int *)0x20200010;
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volatile unsigned int *GPIO_SET1 = (unsigned int *)0x20200020;
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*GPIO_FSEL4 = (*GPIO_FSEL4 & ~(7 << 21)) | (1 << 21);
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*GPIO_SET1 = 1 << 15;
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}

‎lectures/Linking/code/blink-libpi/gpio.c

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#include "gpio.h"
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void gpio_init(void) {
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}
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void gpio_set_function(unsigned int pin, unsigned int function) {
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// TODO: Your code goes here.
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}
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unsigned int gpio_get_function(unsigned int pin) {
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return 0; // TODO: Your code goes here.
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}
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void gpio_set_input(unsigned int pin) {
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// TODO: Your code goes here.
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}
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void gpio_set_output(unsigned int pin) {
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// TODO: your code goes here.
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}
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void gpio_write(unsigned int pin, unsigned int value) {
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// TODO: Your code goes here.
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}
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unsigned int gpio_read(unsigned int pin) {
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return 0; // TODO: Your code goes here.
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}

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