1 | void timer1_asm_irq_handler (void)
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2 | //* Begin
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3 | {
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4 |
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5 | asm volatile(
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6 | " @---------------------------------------------------------------------\n\t"
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7 | " @- File source : irq_timer.s \n\t"
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8 | " @- Object : Assembler timer Interrupt Handler \n\t"
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9 | " @- Author : AT91 Application Group \n\t"
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10 | " @---------------------------------------------------------------------\n\t"
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11 |
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12 | " .text \n\t"
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13 | " .equ AIC_BASE, 0xFFFFF000 \n\t"
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14 | " .equ AIC_IVR, 0x100 \n\t"
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15 | " .equ AIC_EOICR, 0x130 \n\t"
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16 |
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17 | " @- ARM Core Mode and Status Bits \n\t"
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18 | " .equ ARM_MODE_IRQ, 0x12 \n\t"
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19 | " .equ ARM_MODE_SYS, 0x1F \n\t"
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20 | " .equ I_BIT, 0x80 \n\t"
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21 |
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22 | ".macro IRQ_ENTRY reg \n\t"
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23 | " @- Adjust and save LR_irq in IRQ stack \n\t"
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24 | " sub r14, r14, #4 \n\t"
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25 | " stmfd sp!, {r14} \n\t"
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26 |
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27 | " @- Write in the IVR to support Protect Mode \n\t"
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28 | " @- No effect in Normal Mode \n\t"
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29 | " @- De-assert the NIRQ and clear the source in Protect Mode \n\t"
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30 | " ldr r14, =AIC_BASE \n\t"
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31 | " str r14, [r14, #AIC_IVR] \n\t"
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32 |
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33 | "@- Save SPSR and r0 in IRQ stack \n\t"
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34 | " mrs r14, SPSR \n\t"
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35 | " stmfd sp!, {r0, r14} \n\t"
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36 |
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37 | "@;- Enable Interrupt and Switch in SYS Mode \n\t"
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38 | " mrs r0, CPSR \n\t"
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39 | " bic r0, r0, #I_BIT \n\t"
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40 | " orr r0, r0, #ARM_MODE_SYS \n\t"
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41 | " msr CPSR_c, r0 \n\t"
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42 |
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43 | "@- Save scratch/used registers and LR in User Stack \n\t"
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44 | " .ifeq \reg \n\t"
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45 | " stmfd sp!, { r1-r3, r12, r14} \n\t"
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46 | " .else \n\t"
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47 | " stmfd sp!, { r1-r3, $reg, r12, r14} \n\t"
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48 | " .endif \n\t"
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49 | ".endm \n\t"
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50 |
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51 | ".macro IRQ_EXIT reg \n\t"
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52 |
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53 | "@- Restore scratch/used registers and LR from User Stack \n\t"
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54 | " .ifeq \reg \n\t"
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55 | " ldmia sp!, { r1-r3, r12, r14} \n\t"
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56 | " .else \n\t"
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57 | " ldmia sp!, { r1-r3, $reg, r12, r14} \n\t"
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58 | " .endif \n\t"
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59 |
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60 | "@- Disable Interrupt and switch back in IRQ mode \n\t"
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61 | " mrs r0, CPSR \n\t"
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62 | " bic r0, r0, #ARM_MODE_SYS \n\t"
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63 | " orr r0, r0, #I_BIT:OR:ARM_MODE_IRQ \n\t"
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64 | " msr CPSR_c, r0 \n\t"
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65 |
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66 | "@- Mark the End of Interrupt on the AIC \n\t"
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67 | " ldr r0, =AIC_BASE \n\t"
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68 | " str r0, [r0, #AIC_EOICR] \n\t"
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69 |
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70 | "@- Restore SPSR_irq and r0 from IRQ stack \n\t"
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71 | " ldmia sp!, {r0, r14} \n\t"
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72 | " msr SPSR_cxsf, r14 \n\t"
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73 |
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74 | "@- Restore adjusted LR_irq from IRQ stack directly in the PC\n\t"
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75 | " ldmia sp!, {pc}^ \n\t"
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76 | ".endm \n\t"
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77 |
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78 | "@---------------------------------------------------------------\n\t"
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79 | "@- Function : timer1_asm_irq_handler \n\t"
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80 | "@- Treatments : Timer 1 interrupt handler. \n\t"
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81 | "@- Called Functions : timer1_c_irq_handler \n\t"
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82 | "@- Called Macros : IRQ_ENTRY, IRQ_EXIT \n\t"
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83 | "@--------------------------------------------------------------\n\t"
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84 | " .extern timer1_c_irq_handler \n\t"
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85 | " .global timer1_asm_irq_handler \n\t"
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86 | "@- Manage Exception Entry \n\t"
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87 | " IRQ_ENTRY \n\t"
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88 | "@- Call the timer Interrupt C handler \n\t"
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89 | " ldr r1, =timer1_c_irq_handler \n\t"
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90 | " mov r14, pc \n\t"
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91 | " bx r1 \n\t"
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92 | "@- Manage Exception Exit \n\t"
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93 | " IRQ_EXIT \n\t"
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94 | ".end \n\t"
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95 |
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96 | );
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97 | }
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